id stringlengths 9 13 | submitter stringlengths 1 64 ⌀ | authors stringlengths 5 22.9k | title stringlengths 4 245 | comments stringlengths 1 548 ⌀ | journal-ref stringlengths 4 362 ⌀ | doi stringlengths 12 82 ⌀ | report-no stringlengths 2 281 ⌀ | categories stringclasses 793 values | license stringclasses 9 values | orig_abstract stringlengths 24 1.95k | versions listlengths 1 30 | update_date stringlengths 10 10 | authors_parsed listlengths 1 1.74k | abstract stringlengths 21 1.95k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1805.01007 | Ramon Herrera | Ramon Herrera | Reconstructing G-inflation: From the attractors $n_S(N)$ and $r(N)$ | 18 pages and 1 figure. References added and with minor change | Phys. Rev. D 98, 023542 (2018) | 10.1103/PhysRevD.98.023542 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The reconstruction of an inflationary universe in the context of the Galileon
model or G-model, considering as attractors the scalar spectral index $n_S(N)$
and the tensor to scalar ratio $r(N)$ as a function of the number of e-folding
$N$ is studied. By assuming a coupling of the form $G(\phi,X)=g(\phi)\,X$, we
obtain the effective potential $V$ and the coupling parameter $g$ in terms of
the cosmological parameters $n_S$ and $r$ under the slow roll approximation.
From some examples for $n_S(N)$ and $r(N)$, different results for the effective
potential $V(\phi)$ and the coupling parameter $g(\phi)$ are found.
| [
{
"created": "Wed, 2 May 2018 20:33:35 GMT",
"version": "v1"
},
{
"created": "Thu, 14 Jun 2018 20:01:58 GMT",
"version": "v2"
}
] | 2018-08-08 | [
[
"Herrera",
"Ramon",
""
]
] | The reconstruction of an inflationary universe in the context of the Galileon model or G-model, considering as attractors the scalar spectral index $n_S(N)$ and the tensor to scalar ratio $r(N)$ as a function of the number of e-folding $N$ is studied. By assuming a coupling of the form $G(\phi,X)=g(\phi)\,X$, we obtain the effective potential $V$ and the coupling parameter $g$ in terms of the cosmological parameters $n_S$ and $r$ under the slow roll approximation. From some examples for $n_S(N)$ and $r(N)$, different results for the effective potential $V(\phi)$ and the coupling parameter $g(\phi)$ are found. |
1710.06307 | Ritabrata Biswas | Promila Biswas and Ritabrata Biswas | Evolution of Universe as a Homogeneous System : Changes of Scale Factors
with Different Dark Energy EoS-s | 8 pages, 18 figures | Modern Physics Letters A; Vol. 33, No. 19, 1850106 (2018) | 10.1142/S0217732318501067 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We analyse the universe homogeneously filled up by different dark energies.
We calculate the relations between time and the scale factor. We thoroughly
check the differences to be obtained with the changes of different parameters.
$t$ vs $a(t)$ curves are studied. Physical differences between several dark
energy models are studied. We conclude about the future singularities to be
occurred.
| [
{
"created": "Mon, 16 Oct 2017 13:38:18 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Jul 2018 11:20:19 GMT",
"version": "v2"
}
] | 2018-07-26 | [
[
"Biswas",
"Promila",
""
],
[
"Biswas",
"Ritabrata",
""
]
] | We analyse the universe homogeneously filled up by different dark energies. We calculate the relations between time and the scale factor. We thoroughly check the differences to be obtained with the changes of different parameters. $t$ vs $a(t)$ curves are studied. Physical differences between several dark energy models are studied. We conclude about the future singularities to be occurred. |
2307.05673 | Ioannis Gialamas | Ioannis D. Gialamas, Kyriakos Tamvakis | Bimetric Starobinsky model | 7 pages, 3 figures, title slightly edited, matches published version | null | null | null | gr-qc astro-ph.CO hep-th | http://creativecommons.org/licenses/by/4.0/ | The bimetric theory of gravity is an extension of general relativity that
describes a massive spin-$2$ particle in addition to the standard massless
graviton. The theory is based on two dynamical metric tensors with their
interactions constrained by requiring the absence of the so-called
Boulware-Deser ghost. It has been realized that the quantum interactions of
matter fields with gravity are bound to generate modifications to the standard
Einstein-Hilbert action such as quadratic curvature terms. Such a quadratic
Ricci scalar term is present in the so-called Starobinsky model which has been
proven to be rather robust in its inflationary predictions. In the present
article we study a generalization of the Starobinsky model within the bimetric
theory and find that its inflationary behavior stays intact while keeping all
consistency requirements of the bimetric framework. The interpretation of the
massive spin-2 particle as dark matter remains a viable scenario, as in
standard bigravity.
| [
{
"created": "Tue, 11 Jul 2023 18:00:02 GMT",
"version": "v1"
},
{
"created": "Fri, 29 Sep 2023 09:04:54 GMT",
"version": "v2"
}
] | 2023-10-02 | [
[
"Gialamas",
"Ioannis D.",
""
],
[
"Tamvakis",
"Kyriakos",
""
]
] | The bimetric theory of gravity is an extension of general relativity that describes a massive spin-$2$ particle in addition to the standard massless graviton. The theory is based on two dynamical metric tensors with their interactions constrained by requiring the absence of the so-called Boulware-Deser ghost. It has been realized that the quantum interactions of matter fields with gravity are bound to generate modifications to the standard Einstein-Hilbert action such as quadratic curvature terms. Such a quadratic Ricci scalar term is present in the so-called Starobinsky model which has been proven to be rather robust in its inflationary predictions. In the present article we study a generalization of the Starobinsky model within the bimetric theory and find that its inflationary behavior stays intact while keeping all consistency requirements of the bimetric framework. The interpretation of the massive spin-2 particle as dark matter remains a viable scenario, as in standard bigravity. |
1301.3648 | Diego Rubiera-Garcia | J. Diaz-Alonso and D. Rubiera-Garcia | Charged black hole solutions of non-linear electrodynamics and
generalized gauge field theories | 5 pages, 1 figure, extended version of the contribution to the
Proceedings of the Spanish Relativity Meeting 2010 (ERE2010), held in Madrid
University (Complutense), Spain (IOP Publishing) | 2011 J. Phys.: Conf. Ser. 314 012065 | 10.1088/1742-6596/314/1/012065 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We summarize the main features of a class of \emph{asymptotically anomalous}
(asymptotically flat, but non Schwarzschild-like) gravitational configurations
in models of gravitating non-linear electrodynamics in three space dimensions,
whose Lagrangian densities are defined as arbitrary functions of the two field
invariants and constrained by several physical admissibility conditions. This
class of models and their associated electrostatic spherically symmetric black
hole solutions are characterized by the behaviours of the Lagrangian densities
around the vacuum and at the boundary of their domain of definition.
| [
{
"created": "Wed, 16 Jan 2013 10:24:48 GMT",
"version": "v1"
},
{
"created": "Tue, 23 Apr 2013 09:10:18 GMT",
"version": "v2"
}
] | 2013-04-24 | [
[
"Diaz-Alonso",
"J.",
""
],
[
"Rubiera-Garcia",
"D.",
""
]
] | We summarize the main features of a class of \emph{asymptotically anomalous} (asymptotically flat, but non Schwarzschild-like) gravitational configurations in models of gravitating non-linear electrodynamics in three space dimensions, whose Lagrangian densities are defined as arbitrary functions of the two field invariants and constrained by several physical admissibility conditions. This class of models and their associated electrostatic spherically symmetric black hole solutions are characterized by the behaviours of the Lagrangian densities around the vacuum and at the boundary of their domain of definition. |
1305.4512 | Andrea Dapor | Michal Artymowski, Andrea Dapor, Tomasz Pawlowski | Loop quantum cosmology for nonminimally coupled scalar field | 3 pages, 2 figures. To appear in Proceedings of the 13th Marcel
Grossmann Meeting (MG13), Stockholm, Sweden, 1-7 July 2012 | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We perform a LQC-quantization of the FRW cosmological model with nonminimally
coupled scalar field. Making use of a canonical transformation, we recast the
theory in the minimally coupled form (Einstein frame), for which standard LQC
techniques can be applied to find the physical Hilbert space and the dynamics.
We then focus on the semiclassical sector, obtaining a classical effective
Hamiltonian, which can be used to study the dynamics. We show that the
classical singularity is replaced by a "mexican hat"-shaped bounce, joining the
contracting and expanding branches. The model accommodates Higgs-driven
inflation, with more than enough e-folding for any physically meaningful
initial condition.
| [
{
"created": "Mon, 20 May 2013 12:47:51 GMT",
"version": "v1"
}
] | 2013-05-21 | [
[
"Artymowski",
"Michal",
""
],
[
"Dapor",
"Andrea",
""
],
[
"Pawlowski",
"Tomasz",
""
]
] | We perform a LQC-quantization of the FRW cosmological model with nonminimally coupled scalar field. Making use of a canonical transformation, we recast the theory in the minimally coupled form (Einstein frame), for which standard LQC techniques can be applied to find the physical Hilbert space and the dynamics. We then focus on the semiclassical sector, obtaining a classical effective Hamiltonian, which can be used to study the dynamics. We show that the classical singularity is replaced by a "mexican hat"-shaped bounce, joining the contracting and expanding branches. The model accommodates Higgs-driven inflation, with more than enough e-folding for any physically meaningful initial condition. |
2002.00285 | Carlos Augusto Romero Filho | T. A. T. Sanomiya, I. P. Lobo, J. B. Formiga, F. Dahia and C. Romero | An Invariant Approach to Weyl's unified field theory | 20 pages | Phys. Rev. D 102, 124031 (2020) | 10.1103/PhysRevD.102.124031 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We revisit Weyl's unified field theory, which arose in 1918, shortly after
general relativity was discovered. As is well known, in order to extend the
program of geometrization of physics started by Einstein to include the
electromagnetic field, H. Weyl developed a new geometry which constitutes a
kind of generalization of Riemannian geometry. However, despite its
mathematical elegance and beauty, a serious objection was made by Einstein, who
considered Weyl's theory not suitable as a physical theory since it seemed to
lead to the prediction of a not yet observed effect, the so-called "second
clock effect" . In this paper, our aim is to discuss Weyl's proposal anew and
examine its consistency and completeness as a physical theory. Finally, we
propose new directions and possible conceptual changes in the original work. As
an application, we solve the field equations assuming a
Friedmann-Robertson-Walker universe and a perfect fluid as its source. Although
we have entirely abandoned Weyl's atempt to identify the vector field with the
4-dimensional electromagnetic potentials, which here must be simply viewed as
part of the space-time geometry, we believe that in this way we could perhaps
be led to a rich and interesting new modified gravity theory.
| [
{
"created": "Sat, 1 Feb 2020 22:36:53 GMT",
"version": "v1"
}
] | 2021-01-04 | [
[
"Sanomiya",
"T. A. T.",
""
],
[
"Lobo",
"I. P.",
""
],
[
"Formiga",
"J. B.",
""
],
[
"Dahia",
"F.",
""
],
[
"Romero",
"C.",
""
]
] | We revisit Weyl's unified field theory, which arose in 1918, shortly after general relativity was discovered. As is well known, in order to extend the program of geometrization of physics started by Einstein to include the electromagnetic field, H. Weyl developed a new geometry which constitutes a kind of generalization of Riemannian geometry. However, despite its mathematical elegance and beauty, a serious objection was made by Einstein, who considered Weyl's theory not suitable as a physical theory since it seemed to lead to the prediction of a not yet observed effect, the so-called "second clock effect" . In this paper, our aim is to discuss Weyl's proposal anew and examine its consistency and completeness as a physical theory. Finally, we propose new directions and possible conceptual changes in the original work. As an application, we solve the field equations assuming a Friedmann-Robertson-Walker universe and a perfect fluid as its source. Although we have entirely abandoned Weyl's atempt to identify the vector field with the 4-dimensional electromagnetic potentials, which here must be simply viewed as part of the space-time geometry, we believe that in this way we could perhaps be led to a rich and interesting new modified gravity theory. |
1906.07738 | Daniele Vernieri | Daniele Vernieri | Anisotropic fluid spheres in Ho\v{r}ava gravity and Einstein-\ae ther
theory with a non-static \ae ther | v1: 8 pages; v2: 9 pages. Matches published version in PRD | Phys. Rev. D 100, 104021 (2019) | 10.1103/PhysRevD.100.104021 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper we consider spherically symmetric interior spacetimes filled by
anisotropic fluids in the context of Ho\v{r}ava gravity and Einstein-aether
theory. We assume a specific non-static configuration of the aether vector
field and show that the field equations admit a family of exact analytical
solutions which can be obtained if one of the two metric coefficients is
assigned. We study as an illustrative example the case in which the metric of
the interior spacetime reproduces the Newtonian potential of a fluid sphere
with constant density.
| [
{
"created": "Tue, 18 Jun 2019 18:00:36 GMT",
"version": "v1"
},
{
"created": "Mon, 18 Nov 2019 16:15:34 GMT",
"version": "v2"
}
] | 2019-11-19 | [
[
"Vernieri",
"Daniele",
""
]
] | In this paper we consider spherically symmetric interior spacetimes filled by anisotropic fluids in the context of Ho\v{r}ava gravity and Einstein-aether theory. We assume a specific non-static configuration of the aether vector field and show that the field equations admit a family of exact analytical solutions which can be obtained if one of the two metric coefficients is assigned. We study as an illustrative example the case in which the metric of the interior spacetime reproduces the Newtonian potential of a fluid sphere with constant density. |
1904.06365 | Nicola Franchini | Nikolas Andreou, Nicola Franchini, Giulia Ventagli, Thomas P. Sotiriou | Spontaneous scalarization in generalised scalar-tensor theory | Added a term than had accidentally been omitted in equations (24),
(25), (40), (42). Typos corrected. Results unchanged | Phys. Rev. D 99, 124022 (2019) | 10.1103/PhysRevD.99.124022 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Spontaneous scalarization is a mechanism that endows relativistic stars and
black holes with a nontrivial configuration only when their spacetime curvature
exceeds some threshold. The standard way to trigger spontaneous scalarization
is via a tachyonic instability at the linear level, which is eventually
quenched due to the effect of non-linear terms. In this paper, we identify all
of the terms in the Horndeski action that contribute to the (effective) mass
term in the linearized equations and, hence, can cause or contribute to the
tachyonic instability that triggers scalarization.
| [
{
"created": "Fri, 12 Apr 2019 18:07:02 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Jun 2019 08:56:38 GMT",
"version": "v2"
},
{
"created": "Mon, 11 May 2020 14:21:12 GMT",
"version": "v3"
}
] | 2020-05-12 | [
[
"Andreou",
"Nikolas",
""
],
[
"Franchini",
"Nicola",
""
],
[
"Ventagli",
"Giulia",
""
],
[
"Sotiriou",
"Thomas P.",
""
]
] | Spontaneous scalarization is a mechanism that endows relativistic stars and black holes with a nontrivial configuration only when their spacetime curvature exceeds some threshold. The standard way to trigger spontaneous scalarization is via a tachyonic instability at the linear level, which is eventually quenched due to the effect of non-linear terms. In this paper, we identify all of the terms in the Horndeski action that contribute to the (effective) mass term in the linearized equations and, hence, can cause or contribute to the tachyonic instability that triggers scalarization. |
gr-qc/0304048 | Carlos Kozameh | Reinaldo J. Gleiser, Carlos N. Kozameh and Florencia Parisi | On low energy quantum gravity induced effects on the propagation of
light | 12 pages | Class.Quant.Grav. 20 (2003) 4375-4386 | 10.1088/0264-9381/20/20/303 | null | gr-qc | null | Present models describing the interaction of quantum Maxwell and
gravitational fields predict a breakdown of Lorentz invariance and a non
standard dispersion relation in the semiclassical approximation. Comparison
with observational data however, does not support their predictions. In this
work we introduce a different set of ab initio assumptions in the canonical
approach, namely that the homogeneous Maxwell equations are valid in the
semiclassical approximation, and find that the resulting field equations are
Lorentz invariant in the semiclassical limit. We also include a
phenomenological analysis of possible effects on the propagation of light, and
their dependence on energy, in a cosmological context.
| [
{
"created": "Fri, 11 Apr 2003 20:07:29 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Gleiser",
"Reinaldo J.",
""
],
[
"Kozameh",
"Carlos N.",
""
],
[
"Parisi",
"Florencia",
""
]
] | Present models describing the interaction of quantum Maxwell and gravitational fields predict a breakdown of Lorentz invariance and a non standard dispersion relation in the semiclassical approximation. Comparison with observational data however, does not support their predictions. In this work we introduce a different set of ab initio assumptions in the canonical approach, namely that the homogeneous Maxwell equations are valid in the semiclassical approximation, and find that the resulting field equations are Lorentz invariant in the semiclassical limit. We also include a phenomenological analysis of possible effects on the propagation of light, and their dependence on energy, in a cosmological context. |
2108.07572 | Horacio E. Camblong | A. Azizi, H. E. Camblong, A. Chakraborty, C. R. Ordonez, and M. O.
Scully | Quantum optics meets black hole thermodynamics via conformal quantum
mechanics: II. Thermodynamics of acceleration radiation | 31 pages, 1 figure | null | 10.1103/PhysRevD.104.084085 | null | gr-qc hep-th quant-ph | http://creativecommons.org/licenses/by/4.0/ | The thermodynamics of ``horizon brightened acceleration radiation'' (HBAR),
due to a random atomic cloud freely falling into a black hole in a
Boulware-like vacuum, is shown to mimic the thermodynamics of the black hole
itself. The thermodynamic framework is developed in its most general form via a
quantum optics master equation, including rotating (Kerr) black holes and for
any set of initial conditions of the atomic cloud. The HBAR field exhibits
thermal behavior at the Hawking temperature and an area-entropy-flux relation
that resembles the Bekenstein-Hawking entropy. In addition, this general
approach reveals:(i) the existence of an HBAR-black-hole thermodynamic
correspondence that explains the HBAR area-entropy-flux relation;(ii) the
origin of the field entropy from the near-horizon behavior, via conformal
quantum mechanics (CQM).
| [
{
"created": "Tue, 17 Aug 2021 11:53:21 GMT",
"version": "v1"
}
] | 2021-11-03 | [
[
"Azizi",
"A.",
""
],
[
"Camblong",
"H. E.",
""
],
[
"Chakraborty",
"A.",
""
],
[
"Ordonez",
"C. R.",
""
],
[
"Scully",
"M. O.",
""
]
] | The thermodynamics of ``horizon brightened acceleration radiation'' (HBAR), due to a random atomic cloud freely falling into a black hole in a Boulware-like vacuum, is shown to mimic the thermodynamics of the black hole itself. The thermodynamic framework is developed in its most general form via a quantum optics master equation, including rotating (Kerr) black holes and for any set of initial conditions of the atomic cloud. The HBAR field exhibits thermal behavior at the Hawking temperature and an area-entropy-flux relation that resembles the Bekenstein-Hawking entropy. In addition, this general approach reveals:(i) the existence of an HBAR-black-hole thermodynamic correspondence that explains the HBAR area-entropy-flux relation;(ii) the origin of the field entropy from the near-horizon behavior, via conformal quantum mechanics (CQM). |
2306.16469 | R. K. L. Lo | Rico K. L. Lo | Recipes for computing radiation from a Kerr black hole using Generalized
Sasaki-Nakamura formalism: I. Homogeneous solutions | 31 pages, 12 figures | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Central to black hole perturbation theory calculations is the Teukolsky
equation that governs the propagation and the generation of radiation emitted
by Kerr black holes. However, it is plagued by a long-ranged potential
associated to the perturbation equation and hence a direct numerical
integration of the equation is challenging. Sasaki and Nakamura devised a
formulation that transforms the equation into a new equation that is free from
the issue for the case of out-going gravitational radiation. The formulation
was later generalized by Hughes to work for any type of radiation. In this
work, we revamp the Generalized Sasaki-Nakamura (GSN) formalism and explicitly
show the transformations that convert solutions between the Teukolsky and the
GSN formalism for both in-going and out-going radiation of scalar,
electromagnetic and gravitational type. We derive all necessary ingredients for
the GSN formalism to be used in numerical computations. In particular, we
describe a new numerical implementation of the formalism,
GeneralizedSasakiNakamura.jl, that computes homogeneous solutions to both
perturbation equation in the Teukolsky and the GSN formalism. The code works
well at low frequencies and is even better at high frequencies by leveraging
the fact that black holes are highly permeable to waves at high frequencies.
This work lays the foundation for an efficient scheme to compute gravitational
radiation from Kerr black holes and an alternative way to compute quasi-normal
modes of Kerr black holes.
| [
{
"created": "Wed, 28 Jun 2023 18:00:39 GMT",
"version": "v1"
}
] | 2023-06-30 | [
[
"Lo",
"Rico K. L.",
""
]
] | Central to black hole perturbation theory calculations is the Teukolsky equation that governs the propagation and the generation of radiation emitted by Kerr black holes. However, it is plagued by a long-ranged potential associated to the perturbation equation and hence a direct numerical integration of the equation is challenging. Sasaki and Nakamura devised a formulation that transforms the equation into a new equation that is free from the issue for the case of out-going gravitational radiation. The formulation was later generalized by Hughes to work for any type of radiation. In this work, we revamp the Generalized Sasaki-Nakamura (GSN) formalism and explicitly show the transformations that convert solutions between the Teukolsky and the GSN formalism for both in-going and out-going radiation of scalar, electromagnetic and gravitational type. We derive all necessary ingredients for the GSN formalism to be used in numerical computations. In particular, we describe a new numerical implementation of the formalism, GeneralizedSasakiNakamura.jl, that computes homogeneous solutions to both perturbation equation in the Teukolsky and the GSN formalism. The code works well at low frequencies and is even better at high frequencies by leveraging the fact that black holes are highly permeable to waves at high frequencies. This work lays the foundation for an efficient scheme to compute gravitational radiation from Kerr black holes and an alternative way to compute quasi-normal modes of Kerr black holes. |
gr-qc/9703037 | Jose A. Zapata | Jose A. Zapata | A Combinatorial Approach to Diffeomorphism Invariant Quantum Gauge
Theories | 24 pages, 1 fugure | J.Math.Phys. 38 (1997) 5663-5681 | 10.1063/1.532159 | CGPG-97/3-7 | gr-qc hep-lat hep-th | null | Quantum gauge theory in the connection representation uses functions of
holonomies as configuration observables. Physical observables (gauge and
diffeomorphism invariant) are represented in the Hilbert space of physical
states; physical states are gauge and diffeomorphism invariant distributions on
the space of functions of the holonomies of the edges of a certain family of
graphs. Then a family of graphs embedded in the space manifold (satisfying
certain properties) induces a representation of the algebra of physical
observables. We construct a quantum model from the set of piecewise linear
graphs on a piecewise linear manifold, and another manifestly combinatorial
model from graphs defined on a sequence of increasingly refined simplicial
complexes. Even though the two models are different at the kinematical level,
they provide unitarily equivalent representations of the algebra of physical
observables in separable Hilbert spaces of physical states (their s-knot basis
is countable). Hence, the combinatorial framework is compatible with the usual
interpretation of quantum field theory.
| [
{
"created": "Fri, 14 Mar 1997 21:44:32 GMT",
"version": "v1"
}
] | 2016-08-31 | [
[
"Zapata",
"Jose A.",
""
]
] | Quantum gauge theory in the connection representation uses functions of holonomies as configuration observables. Physical observables (gauge and diffeomorphism invariant) are represented in the Hilbert space of physical states; physical states are gauge and diffeomorphism invariant distributions on the space of functions of the holonomies of the edges of a certain family of graphs. Then a family of graphs embedded in the space manifold (satisfying certain properties) induces a representation of the algebra of physical observables. We construct a quantum model from the set of piecewise linear graphs on a piecewise linear manifold, and another manifestly combinatorial model from graphs defined on a sequence of increasingly refined simplicial complexes. Even though the two models are different at the kinematical level, they provide unitarily equivalent representations of the algebra of physical observables in separable Hilbert spaces of physical states (their s-knot basis is countable). Hence, the combinatorial framework is compatible with the usual interpretation of quantum field theory. |
2101.06135 | Konstantinos Xenos | Konstantinos Xenos | An Introduction to FRW Cosmology and dark energy models | null | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this thesis we will focus on Einstein's interpretation of gravity. We will
examine how the most famous equations in cosmology are derived from GR and also
some results of cosmological significance. We will see how combining that with
observational data forces us to consider some form of dark energy or vacuum
energy. So we will conclude with some of the more well-known models for dark
energy and examine how the dynamics of dark energy can lead us to the so-called
cosmological inflation.
| [
{
"created": "Fri, 15 Jan 2021 14:27:47 GMT",
"version": "v1"
}
] | 2021-01-18 | [
[
"Xenos",
"Konstantinos",
""
]
] | In this thesis we will focus on Einstein's interpretation of gravity. We will examine how the most famous equations in cosmology are derived from GR and also some results of cosmological significance. We will see how combining that with observational data forces us to consider some form of dark energy or vacuum energy. So we will conclude with some of the more well-known models for dark energy and examine how the dynamics of dark energy can lead us to the so-called cosmological inflation. |
0706.3212 | Patricio S. Letelier | Val\'eria M. Rosa and Patricio S. Letelier | Linear Stability of Closed Timelike Geodesics | 7 pages, RevTex, minor changes to match the published version | in Goedel-type spacetimes: History and new developments, M. Plaue
and M. Scherfner Eds., Kurt Goedel Society Collegium Logicum v. X, pp.
129-139 (2010) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The linear stability of closed timelike geodesics (CTGs) is analyzed in two
spacetimes with cylindrical sources, an infinite rotating dust cylinder, and a
cylindrical cloud of static cosmic strings with a central spinning string. We
also study the existence and linear stability of closed timelike curves in
spacetimes that share some common features with the G\"odel universe
(G\"odel-type spacetimes). In this case the existence of CTGs depends on the
`background' metric. The CTGs in a subclass of inhomogeneous stationary
cosmological solutions of the Einstein-Maxwell equations with topology $
S^3\times \mathbb R$ are also examined.
| [
{
"created": "Thu, 21 Jun 2007 19:57:29 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Jan 2011 19:24:30 GMT",
"version": "v2"
}
] | 2011-01-26 | [
[
"Rosa",
"Valéria M.",
""
],
[
"Letelier",
"Patricio S.",
""
]
] | The linear stability of closed timelike geodesics (CTGs) is analyzed in two spacetimes with cylindrical sources, an infinite rotating dust cylinder, and a cylindrical cloud of static cosmic strings with a central spinning string. We also study the existence and linear stability of closed timelike curves in spacetimes that share some common features with the G\"odel universe (G\"odel-type spacetimes). In this case the existence of CTGs depends on the `background' metric. The CTGs in a subclass of inhomogeneous stationary cosmological solutions of the Einstein-Maxwell equations with topology $ S^3\times \mathbb R$ are also examined. |
2201.09703 | Shao-Jun Zhang | Shao-Jun Zhang | Spherical black holes with minimally coupled scalar cloud/hair in
Einstein-Born-Infeld gravity | 18 pages, 8 figures. Minor modifications to match published version | Eur. Phys. J. C 82, 501 (2022) | 10.1140/epjc/s10052-022-10464-0 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Previous studies showed that, in the presence of a simple and well-motivated
self-interaction scalar potential, asymptotically flat and spherical black
holes can carry minimally coupled and charged scalar cloud/hair in
Einstein-Maxwell gravity. We extend these studies to Einstein-Born-Infeld
gravity to consider the effect of nonlinearity of the electromagnetic field.
Series of spherical cloudy/hairy black hole solutions are constructed
numerically. Results show that increasing the Born-Infeld coupling constant $b$
will make the domain of existence of the solution shrink or even disappear when
$b$ is large enough. This implies that, competing with the gravitation,
nonlinearity of the electromagnetic field will make the formation of scalar
cloud/hair harder or even impossible.
| [
{
"created": "Mon, 24 Jan 2022 14:13:41 GMT",
"version": "v1"
},
{
"created": "Tue, 8 Feb 2022 01:22:22 GMT",
"version": "v2"
},
{
"created": "Thu, 2 Jun 2022 10:43:20 GMT",
"version": "v3"
}
] | 2022-06-09 | [
[
"Zhang",
"Shao-Jun",
""
]
] | Previous studies showed that, in the presence of a simple and well-motivated self-interaction scalar potential, asymptotically flat and spherical black holes can carry minimally coupled and charged scalar cloud/hair in Einstein-Maxwell gravity. We extend these studies to Einstein-Born-Infeld gravity to consider the effect of nonlinearity of the electromagnetic field. Series of spherical cloudy/hairy black hole solutions are constructed numerically. Results show that increasing the Born-Infeld coupling constant $b$ will make the domain of existence of the solution shrink or even disappear when $b$ is large enough. This implies that, competing with the gravitation, nonlinearity of the electromagnetic field will make the formation of scalar cloud/hair harder or even impossible. |
1705.08978 | Matthew Pitkin | Matthew Pitkin, Maximiliano Isi, John Veitch and Graham Woan | A nested sampling code for targeted searches for continuous
gravitational waves from pulsars | 46 pages, 34 figures. Document detailing and characterising analysis
software for a gravitational wave search. The document source, example
scripts and jupyter notebooks used can be found at
https://github.com/mattpitkin/CW_nested_sampling_doc | null | null | null | gr-qc astro-ph.IM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This document describes a code to perform parameter estimation and model
selection in targeted searches for continuous gravitational waves from known
pulsars using data from ground-based gravitational wave detectors. We describe
the general workings of the code and characterise it on simulated data
containing both noise and simulated signals. We also show how it performs
compared to a previous MCMC and grid-based approach to signal parameter
estimation. Details how to run the code in a variety of cases are provided in
Appendix A.
| [
{
"created": "Wed, 24 May 2017 22:04:22 GMT",
"version": "v1"
}
] | 2017-05-26 | [
[
"Pitkin",
"Matthew",
""
],
[
"Isi",
"Maximiliano",
""
],
[
"Veitch",
"John",
""
],
[
"Woan",
"Graham",
""
]
] | This document describes a code to perform parameter estimation and model selection in targeted searches for continuous gravitational waves from known pulsars using data from ground-based gravitational wave detectors. We describe the general workings of the code and characterise it on simulated data containing both noise and simulated signals. We also show how it performs compared to a previous MCMC and grid-based approach to signal parameter estimation. Details how to run the code in a variety of cases are provided in Appendix A. |
2008.02680 | Pedro Bargue\~no | Pedro Bargue\~no | Some global, analytical and topological properties of regular black
holes | Comments added following suggestions of the referees. Accepted in
Phys. Rev. D | Phys. Rev. D 102, 104028 (2020) | 10.1103/PhysRevD.102.104028 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we study regular black holes from a global perspective looking
for evading some of the well-known singularity theorems by using their
"reverses". Then, model geometries for the slices of typical spherically
symmetric, (locally) static four dimensional regular black hole solutions are
described from both an analytical and a topological point of view. While the
finiteness of both the scalar and Kretchmann curvature of the slices around the
regular center determines the geometry of the core, the positive answer to the
Poincar\'e conjecture assures that, under two assumptions, its topology is that
of a three-sphere. However, in general, the cores are shown to be $S^3$, $H^3$,
$\mathbb{R}\times S^1$ or $S^1\times S^2$, depending whether a de Sitter, anti
de Sitter, Nariai or Bertotti-Robinson geometries are employed to describe the
slices at the regular center. Then, a description of the aforementioned slices
in terms of Seifert fibre spaces is given in order to show that the Euler
characteristic of the bundle can be used to track the transition between the
core of the regular black hole and the rest of the slices in most of the cases
considered in the literature. After Geroch and Tipler's theorems are employed
to study the consequences of topology change on regular black hole spacetimes,
we show that Borde and Vilenkin's singularity theorem is used to restrict their
possible types. We end by noting that Nariai cores can be safely used to
construct regular black holes without topology changes.
| [
{
"created": "Thu, 6 Aug 2020 14:24:10 GMT",
"version": "v1"
},
{
"created": "Thu, 20 Aug 2020 11:00:37 GMT",
"version": "v2"
},
{
"created": "Tue, 13 Oct 2020 13:55:29 GMT",
"version": "v3"
}
] | 2020-11-18 | [
[
"Bargueño",
"Pedro",
""
]
] | In this work we study regular black holes from a global perspective looking for evading some of the well-known singularity theorems by using their "reverses". Then, model geometries for the slices of typical spherically symmetric, (locally) static four dimensional regular black hole solutions are described from both an analytical and a topological point of view. While the finiteness of both the scalar and Kretchmann curvature of the slices around the regular center determines the geometry of the core, the positive answer to the Poincar\'e conjecture assures that, under two assumptions, its topology is that of a three-sphere. However, in general, the cores are shown to be $S^3$, $H^3$, $\mathbb{R}\times S^1$ or $S^1\times S^2$, depending whether a de Sitter, anti de Sitter, Nariai or Bertotti-Robinson geometries are employed to describe the slices at the regular center. Then, a description of the aforementioned slices in terms of Seifert fibre spaces is given in order to show that the Euler characteristic of the bundle can be used to track the transition between the core of the regular black hole and the rest of the slices in most of the cases considered in the literature. After Geroch and Tipler's theorems are employed to study the consequences of topology change on regular black hole spacetimes, we show that Borde and Vilenkin's singularity theorem is used to restrict their possible types. We end by noting that Nariai cores can be safely used to construct regular black holes without topology changes. |
gr-qc/9603024 | K. Kokkotas | Kostas D. Kokkotas | Pulsating relativistic stars | 17 pages, l-school.sty, 6 postscript figures, 2.2Mb simulation upon
request | in Relativistic Gravitation and Gravitational Radiation, Eds J-A.
Marck and J-P Lasota, Cambridge Cantemporary Astrophysics (1997) page 89 | null | null | gr-qc | null | In this paper we review the recent developments in the relativistic theory of
stellar pulsations with special emphasis on the spacetime or w-modes. We
discuss also the excitation of these modes and the information about the
neutron star that we will be able to mine from their detection. The paper will
appear in the Proceedings of the Les Houches School on Astrophysical Sources of
Gravitational Radiation, 1995, edited by J.-A. Marck and J.-P. Lasota to be
published by Springer-Verlag.
| [
{
"created": "Fri, 15 Mar 1996 13:52:44 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Kokkotas",
"Kostas D.",
""
]
] | In this paper we review the recent developments in the relativistic theory of stellar pulsations with special emphasis on the spacetime or w-modes. We discuss also the excitation of these modes and the information about the neutron star that we will be able to mine from their detection. The paper will appear in the Proceedings of the Les Houches School on Astrophysical Sources of Gravitational Radiation, 1995, edited by J.-A. Marck and J.-P. Lasota to be published by Springer-Verlag. |
1404.1500 | Jesper M{\o}ller Grimstrup | Johannes Aastrup and Jesper M. Grimstrup | The Quantum Holonomy-Diffeomorphism Algebra & Quantum Gravity | 20 pages, 4 figures | IJMPA, 2016, Volume No.31, Issue No. 10 | 10.1142/S0217751X16500482 | null | gr-qc hep-th math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We introduce the Quantum Holonomy-Diffeomorphism *-algebra, which is
generated by holonomy-diffeomorphisms on a 3-dimensional manifold and
translations on a space of SU(2)-connections. We show that this algebra encodes
the canonical commutation relations of canonical quantum gravity formulated in
terms of Ashtekar variables. Furthermore, we show that semi-classical states
exist on the holonomy-diffeomorphism part of the algebra but that these states
cannot be extended to the full algebra. Via a Dirac type operator we derive a
certain class of unbounded operators that act in the GNS construction of the
semi-classical states. These unbounded operators are the type of operators,
which we have previously shown to entail the spatial 3-dimensional Dirac
operator and Dirac Hamiltonian in a semi-classical limit. Finally, we show that
the structure of the Hamilton constraint emerges from a Yang-Mills type
operator over the space of SU(2)-connections.
| [
{
"created": "Sat, 5 Apr 2014 18:23:54 GMT",
"version": "v1"
},
{
"created": "Fri, 22 Jan 2016 19:31:28 GMT",
"version": "v2"
}
] | 2016-04-12 | [
[
"Aastrup",
"Johannes",
""
],
[
"Grimstrup",
"Jesper M.",
""
]
] | We introduce the Quantum Holonomy-Diffeomorphism *-algebra, which is generated by holonomy-diffeomorphisms on a 3-dimensional manifold and translations on a space of SU(2)-connections. We show that this algebra encodes the canonical commutation relations of canonical quantum gravity formulated in terms of Ashtekar variables. Furthermore, we show that semi-classical states exist on the holonomy-diffeomorphism part of the algebra but that these states cannot be extended to the full algebra. Via a Dirac type operator we derive a certain class of unbounded operators that act in the GNS construction of the semi-classical states. These unbounded operators are the type of operators, which we have previously shown to entail the spatial 3-dimensional Dirac operator and Dirac Hamiltonian in a semi-classical limit. Finally, we show that the structure of the Hamilton constraint emerges from a Yang-Mills type operator over the space of SU(2)-connections. |
1205.2019 | Alejandro Perez | Alejandro Perez | The Spin Foam Approach to Quantum Gravity | To appear in Living Reviews in Relativity | null | 10.12942/lrr-2013-3 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | This article reviews the present status of the spin foam approach to the
quantization of gravity. Special attention is payed to the pedagogical
presentation of the recently introduced new models for four dimensional quantum
gravity. The models are motivated by a suitable implementation of the path
integral quantization of the Plebanski formulation of gravity on a simplicial
regularization. The article also includes a self-contained treatment of the 2+1
gravity. The simple nature of the latter provides the basis and a perspective
for the analysis of both conceptual and technical issues that remain open in
four dimensions.
| [
{
"created": "Wed, 9 May 2012 16:18:15 GMT",
"version": "v1"
}
] | 2015-06-05 | [
[
"Perez",
"Alejandro",
""
]
] | This article reviews the present status of the spin foam approach to the quantization of gravity. Special attention is payed to the pedagogical presentation of the recently introduced new models for four dimensional quantum gravity. The models are motivated by a suitable implementation of the path integral quantization of the Plebanski formulation of gravity on a simplicial regularization. The article also includes a self-contained treatment of the 2+1 gravity. The simple nature of the latter provides the basis and a perspective for the analysis of both conceptual and technical issues that remain open in four dimensions. |
1203.3615 | Vladimir Folomeev | Vladimir Dzhunushaliev, Vladimir Folomeev, Burkhard Kleihaus, Jutta
Kunz | Mixed neutron-star-plus-wormhole systems: Equilibrium configurations | 18 pages, 3 figures, minor corrections to content, references added,
version published in PRD | Phys. Rev. D 85, 124028 (2012) | 10.1103/PhysRevD.85.124028 | null | gr-qc astro-ph.SR | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study gravitationally bound, spherically symmetric equilibrium
configurations consisting of ordinary (neutron-star) matter and of a
phantom/ghost scalar field which provides the nontrivial topology in the
system. For such mixed configurations, we show the existence of static,
regular, asymptotically flat general relativistic solutions. Based on the
energy approach, we discuss the stability as a function of the core density of
the neutron matter for various sizes of the wormhole throat.
| [
{
"created": "Fri, 16 Mar 2012 04:53:16 GMT",
"version": "v1"
},
{
"created": "Sun, 24 Jun 2012 14:15:49 GMT",
"version": "v2"
}
] | 2012-06-26 | [
[
"Dzhunushaliev",
"Vladimir",
""
],
[
"Folomeev",
"Vladimir",
""
],
[
"Kleihaus",
"Burkhard",
""
],
[
"Kunz",
"Jutta",
""
]
] | We study gravitationally bound, spherically symmetric equilibrium configurations consisting of ordinary (neutron-star) matter and of a phantom/ghost scalar field which provides the nontrivial topology in the system. For such mixed configurations, we show the existence of static, regular, asymptotically flat general relativistic solutions. Based on the energy approach, we discuss the stability as a function of the core density of the neutron matter for various sizes of the wormhole throat. |
gr-qc/9803096 | Richard Woodard | R. P. Woodard (University of Florida at Gainesville) | Particles As Bound States In Their Own Potentials | 15 pages, plain TeX | null | null | UFIFT-HEP-98-3 | gr-qc hep-th | null | I consider the problem of computing the mass of a charged, gravitating
particle in quantum field theory. It is shown how solving for the first
quantized propagator of a particle in the presence of its own potentials
reproduces the gauge and general coordinate invariant sum over an infinite
class of diagrams. The distinguishing feature of this class of diagrams is that
all closed loops contain part of the continuous matter line running from early
to late times. The next order term would have one closed loop external to the
continuous matter line, and so on. I argue that the gravitational potentials in
the 0-th order term may permit the formation of bound states, which would then
dominate the propagator. It is conceivable that this provides an tractable
technique for computing the masses of fundamental particles from first
principles. It is also conceivable that the expansion in external loops permits
gravity to regulate certain ultraviolet divergences.
| [
{
"created": "Tue, 31 Mar 1998 02:49:34 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Woodard",
"R. P.",
"",
"University of Florida at Gainesville"
]
] | I consider the problem of computing the mass of a charged, gravitating particle in quantum field theory. It is shown how solving for the first quantized propagator of a particle in the presence of its own potentials reproduces the gauge and general coordinate invariant sum over an infinite class of diagrams. The distinguishing feature of this class of diagrams is that all closed loops contain part of the continuous matter line running from early to late times. The next order term would have one closed loop external to the continuous matter line, and so on. I argue that the gravitational potentials in the 0-th order term may permit the formation of bound states, which would then dominate the propagator. It is conceivable that this provides an tractable technique for computing the masses of fundamental particles from first principles. It is also conceivable that the expansion in external loops permits gravity to regulate certain ultraviolet divergences. |
2210.09544 | V. G. Gurzadyan | A.A.Kocharyan, M.Samsonyan, V.G.Gurzadyan | Gravitational waves as waveguides | 8 pages, 2 figs; Eur Phys J Plus (in press) | Eur. Phys. J. Plus 137, 1133 (2022) | 10.1140/epjp/s13360-022-03359-2 | null | gr-qc astro-ph.IM | http://creativecommons.org/licenses/by/4.0/ | We show that gravitational waves can act as waveguides for electromagnetic
radiation, that is if the latter is initially aligned with the gravitational
waves, then the alignment will survive during the propagation. The analysis is
performed using the Hamiltonian formalism and the Jacobi equation for null
geodesics and conditions for certain cases of polarization of the waves are
obtained. The effect of waveguiding by the gravitational waves can influence
the interpretation of associated gravitational and electromagnetic wave events,
since the latter cannot necessarily obey the inverse square decay law for
intensity.
| [
{
"created": "Tue, 18 Oct 2022 02:44:10 GMT",
"version": "v1"
}
] | 2022-10-21 | [
[
"Kocharyan",
"A. A.",
""
],
[
"Samsonyan",
"M.",
""
],
[
"Gurzadyan",
"V. G.",
""
]
] | We show that gravitational waves can act as waveguides for electromagnetic radiation, that is if the latter is initially aligned with the gravitational waves, then the alignment will survive during the propagation. The analysis is performed using the Hamiltonian formalism and the Jacobi equation for null geodesics and conditions for certain cases of polarization of the waves are obtained. The effect of waveguiding by the gravitational waves can influence the interpretation of associated gravitational and electromagnetic wave events, since the latter cannot necessarily obey the inverse square decay law for intensity. |
1305.2133 | Jos\'e Villanueva | Norman Cruz, Marco Olivares and J. R. Villanueva | Geodesic Structure of Lifshitz Black Holes in 2+1 Dimensions | 10 pages, 6 figures, accepted for publication in Eur. Phys. J. C | null | 10.1140/epjc/s10052-013-2485-8 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a study of the geodesic equations of a black hole space-time which
is a solution of the three-dimensional NMG theory and is asymptotically
Lifshitz with $z=3$ and $d=1$ as found in [Ayon-Beato E., Garbarz A., Giribet
G. and Hassaine M., Phys. Rev. {\bf D} 80, 104029 (2009)]. By means of the
corresponding effective potentials for massive particles and photons we find
the allowed motions by the energy levels. Exact solutions for radial and
non-radial geodesics are given in terms of the Weierstrass elliptic $\wp$,
$\sigma$, and $\zeta$ functions.
| [
{
"created": "Thu, 9 May 2013 16:13:28 GMT",
"version": "v1"
},
{
"created": "Mon, 1 Jul 2013 16:05:57 GMT",
"version": "v2"
}
] | 2013-07-02 | [
[
"Cruz",
"Norman",
""
],
[
"Olivares",
"Marco",
""
],
[
"Villanueva",
"J. R.",
""
]
] | We present a study of the geodesic equations of a black hole space-time which is a solution of the three-dimensional NMG theory and is asymptotically Lifshitz with $z=3$ and $d=1$ as found in [Ayon-Beato E., Garbarz A., Giribet G. and Hassaine M., Phys. Rev. {\bf D} 80, 104029 (2009)]. By means of the corresponding effective potentials for massive particles and photons we find the allowed motions by the energy levels. Exact solutions for radial and non-radial geodesics are given in terms of the Weierstrass elliptic $\wp$, $\sigma$, and $\zeta$ functions. |
1208.6160 | Emma Jakobsson | Emma Jakobsson | How trapped surfaces jump in 2+1 dimensions | 8 pages, 3 figures | Class. Quantum Grav. 30 (2013) 065022 | 10.1088/0264-9381/30/6/065022 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | When a lump of matter falls into a black hole it is expected that a
marginally trapped tube when hit moves outwards everywhere, even in regions not
yet in causal contact with the infalling matter. But to describe this
phenomenon analytically in 3+1 dimensions is difficult since gravitational
radiation is emitted. By considering a particle falling into a toy model of a
black hole in 2+1 dimensions an exact description of this non-local behaviour
of a marginally trapped tube is found.
| [
{
"created": "Thu, 30 Aug 2012 13:04:08 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Mar 2013 14:31:20 GMT",
"version": "v2"
},
{
"created": "Tue, 12 Mar 2013 14:58:38 GMT",
"version": "v3"
}
] | 2013-03-13 | [
[
"Jakobsson",
"Emma",
""
]
] | When a lump of matter falls into a black hole it is expected that a marginally trapped tube when hit moves outwards everywhere, even in regions not yet in causal contact with the infalling matter. But to describe this phenomenon analytically in 3+1 dimensions is difficult since gravitational radiation is emitted. By considering a particle falling into a toy model of a black hole in 2+1 dimensions an exact description of this non-local behaviour of a marginally trapped tube is found. |
0911.2698 | Simone Mercuri | Massimiliano Lattanzi, Simone Mercuri | A solution of the strong CP problem via the Peccei-Quinn mechanism
through the Nieh-Yan modified gravity and cosmological implications | V1: 8 pages, 1 figure. V2: no significant changes, slight change in
the title, some references added, version accepted for publication in PRD | Phys.Rev.D81:125015,2010 | 10.1103/PhysRevD.81.125015 | null | gr-qc astro-ph.CO hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | By identifying the recently introduced Barbero-Immirzi field with the QCD
axion, the strong CP problem can be solved through the Peccei-Quinn mechanism.
A specific energy scale for the Peccei-Quinn symmetry breaking is naturally
predicted by this model. This provides a complete dynamical setting to evaluate
the contribution of such an axion to the cold dark matter content of the
Universe. Furthermore, a tight upper bound on the tensor-to-scalar ratio
production of primordial gravitational waves can be fixed, representing a
strong experimental test for this model.
| [
{
"created": "Fri, 13 Nov 2009 20:58:18 GMT",
"version": "v1"
},
{
"created": "Wed, 23 Jun 2010 17:57:56 GMT",
"version": "v2"
}
] | 2014-11-20 | [
[
"Lattanzi",
"Massimiliano",
""
],
[
"Mercuri",
"Simone",
""
]
] | By identifying the recently introduced Barbero-Immirzi field with the QCD axion, the strong CP problem can be solved through the Peccei-Quinn mechanism. A specific energy scale for the Peccei-Quinn symmetry breaking is naturally predicted by this model. This provides a complete dynamical setting to evaluate the contribution of such an axion to the cold dark matter content of the Universe. Furthermore, a tight upper bound on the tensor-to-scalar ratio production of primordial gravitational waves can be fixed, representing a strong experimental test for this model. |
1509.08788 | Daniel Coumbe | Jan Ambjorn, Daniel Coumbe, Jakub Gizbert-Studnicki, Jerzy Jurkiewicz | Recent results in CDT quantum gravity | 6 pages, 3 figures, 1 table. Contribution to the proceedings of MG14,
Rome July 2015. Added a footnote and references | null | null | null | gr-qc hep-lat hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We review some recent results from the causal dynamical triangulation (CDT)
approach to quantum gravity. We review recent observations of dimensional
reduction at a number of previously undetermined points in the parameter space
of CDT, and discuss their possible relevance to the asymptotic safety scenario.
We also present an updated phase diagram of CDT, discussing properties of a
newly discovered phase and its possible relation to a signature change of the
metric.
| [
{
"created": "Tue, 29 Sep 2015 14:59:36 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Oct 2015 08:46:48 GMT",
"version": "v2"
}
] | 2015-10-13 | [
[
"Ambjorn",
"Jan",
""
],
[
"Coumbe",
"Daniel",
""
],
[
"Gizbert-Studnicki",
"Jakub",
""
],
[
"Jurkiewicz",
"Jerzy",
""
]
] | We review some recent results from the causal dynamical triangulation (CDT) approach to quantum gravity. We review recent observations of dimensional reduction at a number of previously undetermined points in the parameter space of CDT, and discuss their possible relevance to the asymptotic safety scenario. We also present an updated phase diagram of CDT, discussing properties of a newly discovered phase and its possible relation to a signature change of the metric. |
1811.11797 | Debabrata Deb | Debabrata Deb, Shounak Ghosh, S.K. Maurya, Maxim Khlopov and Saibal
Ray | Anisotropic compact stars in f(T) gravity under Karmarkar condition | 20 pages, 11 figures, 4 tables | TECH VISTAS, VOL. 1, NO. 1 , NOV. 2018 | null | null | gr-qc | http://creativecommons.org/licenses/by-nc-sa/4.0/ | In this study, we present a generalized spherically symmetric, anisotropic
and static compact stellar model in $f(T)$ gravity, where $T$ represents the
torsion scalar. By employing the Karmarkar condition we have obtained embedding
class 1 metric from the general spherically metric of class 2 and the solutions
of the Einstein field equations (EFE) has been presented with the choice of
suitable parametric values of $n$ under a simplified linear form of $f(T)$
gravity reads as $f(T)=A+BT$, where $A$ and $B$ are two constants. By matching
the interior spacetime metric with the exterior Schwarzschild metric at the
surface and considering the values of mass and radius of the compact stars we
obtain the values of the unknown constants. We have presented further a
detailed analysis of the physical acceptability and examined the stability of
the stellar configuration by studying the energy conditions, generalized
Tolman-Oppenheimer-Volkov (TOV) equation, Herrera cracking concept, adiabatic
index, etc. In the investigation, we predict numerical values of the central
density, surface density, central pressure, etc., in a tabular form taking
different values of $n$ specifically for $LMC~X-4$, $Cen~X-3$ and $SMC~X-1$ as
the representative of compact star candidates.
| [
{
"created": "Wed, 28 Nov 2018 19:40:36 GMT",
"version": "v1"
}
] | 2018-11-30 | [
[
"Deb",
"Debabrata",
""
],
[
"Ghosh",
"Shounak",
""
],
[
"Maurya",
"S. K.",
""
],
[
"Khlopov",
"Maxim",
""
],
[
"Ray",
"Saibal",
""
]
] | In this study, we present a generalized spherically symmetric, anisotropic and static compact stellar model in $f(T)$ gravity, where $T$ represents the torsion scalar. By employing the Karmarkar condition we have obtained embedding class 1 metric from the general spherically metric of class 2 and the solutions of the Einstein field equations (EFE) has been presented with the choice of suitable parametric values of $n$ under a simplified linear form of $f(T)$ gravity reads as $f(T)=A+BT$, where $A$ and $B$ are two constants. By matching the interior spacetime metric with the exterior Schwarzschild metric at the surface and considering the values of mass and radius of the compact stars we obtain the values of the unknown constants. We have presented further a detailed analysis of the physical acceptability and examined the stability of the stellar configuration by studying the energy conditions, generalized Tolman-Oppenheimer-Volkov (TOV) equation, Herrera cracking concept, adiabatic index, etc. In the investigation, we predict numerical values of the central density, surface density, central pressure, etc., in a tabular form taking different values of $n$ specifically for $LMC~X-4$, $Cen~X-3$ and $SMC~X-1$ as the representative of compact star candidates. |
1712.07433 | Jacek Jezierski | Pawe{\l} Czajka, Jacek Jezierski | Conformal Yano-Killing tensors for space-times with cosmological
constant | 27 pages | Acta Physica Pol B 49 (2018) | 10.5506/APhysPolB.49.785 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present a new method for constructing conformal Yano-Killing tensors in
five-di\-men\-sio\-nal Anti-de Sitter space-time. The found tensors are
represented in two different coordinate systems. We also discuss, in terms of
CYK tensors, global charges which are well defined for asymptotically
(five-dimensional) Anti-de Sitter space-time. Additionally in Appendix we
present our own derivation of conformal Killing one-forms in four-dimensional
Anti-de Sitter space-time as an application of the Theorem presented in the
paper.
| [
{
"created": "Wed, 20 Dec 2017 11:57:57 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Jan 2018 19:44:14 GMT",
"version": "v2"
},
{
"created": "Sun, 22 Apr 2018 12:42:18 GMT",
"version": "v3"
}
] | 2018-10-29 | [
[
"Czajka",
"Paweł",
""
],
[
"Jezierski",
"Jacek",
""
]
] | We present a new method for constructing conformal Yano-Killing tensors in five-di\-men\-sio\-nal Anti-de Sitter space-time. The found tensors are represented in two different coordinate systems. We also discuss, in terms of CYK tensors, global charges which are well defined for asymptotically (five-dimensional) Anti-de Sitter space-time. Additionally in Appendix we present our own derivation of conformal Killing one-forms in four-dimensional Anti-de Sitter space-time as an application of the Theorem presented in the paper. |
gr-qc/9811040 | Andrew Liddle | Luis E Mendes and Andrew R Liddle (Imperial College) | Early cosmology and the stochastic gravitational wave background | 17 pages RevTeX file with eight figures incorporated (uses RevTeX and
epsf). No modifications to results but substantial changes to discussion | null | 10.1103/PhysRevD.60.063508 | null | gr-qc astro-ph | null | The epoch when the Universe had a temperature higher than a GeV is long
before any time at which we have reliable observations constraining the
cosmological evolution. For example, the occurrence of a second burst of
inflation (sometimes called thermal inflation) at a lower energy scale than
standard inflation, or a short epoch of early matter domination, cannot be
ruled out by present cosmological data. The cosmological stochastic
gravitational wave background, on scales accessible to interferometer
detection, is sensitive to non-standard cosmologies of this type. We consider
the implications of such alternative models both for ground-based experiments
such as LIGO and space-based proposals such as LISA. We show that a second
burst of inflation leads to a scale-dependent reduction in the spectrum.
Applied to conventional inflation, this further reduces an already
disappointingly low signal. In the pre big bang scenario, where a much more
potent signal is possible, the amplitude is reduced but the background remains
observable by LISA in certain parameter space regions. In each case, a second
epoch of inflation induces oscillatory features into the spectrum in a manner
analogous to the acoustic peaks in the density perturbation spectrum. On LIGO
scales, perturbations can only survive through thermal inflation with
detectable amplitudes if their amplitudes were at one time so large that linear
perturbation theory is inadequate. Although for an epoch of early matter
domination the reduction in the expected signal is not as large as the one
caused by a second burst of inflation, the detection in the context of the pre
big bang scenario may not be possible since the spectrum peaks around the LIGO
frequency window and for lower frequencies behaves as $f^3$.
| [
{
"created": "Thu, 12 Nov 1998 09:56:46 GMT",
"version": "v1"
},
{
"created": "Thu, 13 May 1999 16:53:57 GMT",
"version": "v2"
}
] | 2009-10-31 | [
[
"Mendes",
"Luis E",
"",
"Imperial College"
],
[
"Liddle",
"Andrew R",
"",
"Imperial College"
]
] | The epoch when the Universe had a temperature higher than a GeV is long before any time at which we have reliable observations constraining the cosmological evolution. For example, the occurrence of a second burst of inflation (sometimes called thermal inflation) at a lower energy scale than standard inflation, or a short epoch of early matter domination, cannot be ruled out by present cosmological data. The cosmological stochastic gravitational wave background, on scales accessible to interferometer detection, is sensitive to non-standard cosmologies of this type. We consider the implications of such alternative models both for ground-based experiments such as LIGO and space-based proposals such as LISA. We show that a second burst of inflation leads to a scale-dependent reduction in the spectrum. Applied to conventional inflation, this further reduces an already disappointingly low signal. In the pre big bang scenario, where a much more potent signal is possible, the amplitude is reduced but the background remains observable by LISA in certain parameter space regions. In each case, a second epoch of inflation induces oscillatory features into the spectrum in a manner analogous to the acoustic peaks in the density perturbation spectrum. On LIGO scales, perturbations can only survive through thermal inflation with detectable amplitudes if their amplitudes were at one time so large that linear perturbation theory is inadequate. Although for an epoch of early matter domination the reduction in the expected signal is not as large as the one caused by a second burst of inflation, the detection in the context of the pre big bang scenario may not be possible since the spectrum peaks around the LIGO frequency window and for lower frequencies behaves as $f^3$. |
1402.0788 | Llu\'is Bel | Ll. Bel | Earth and Moon orbital anomalies | typos corrected, 2 references added | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A time-dependent gravitational constant or mass would correctly describe the
suspected increasing of both: the Astronomical unit and the eccentricity of the
Lunar orbit around the Earth.
| [
{
"created": "Mon, 3 Feb 2014 08:14:18 GMT",
"version": "v1"
},
{
"created": "Tue, 18 Feb 2014 08:45:28 GMT",
"version": "v2"
}
] | 2014-02-19 | [
[
"Bel",
"Ll.",
""
]
] | A time-dependent gravitational constant or mass would correctly describe the suspected increasing of both: the Astronomical unit and the eccentricity of the Lunar orbit around the Earth. |
2201.08700 | Rajes Ghosh | Kabir Chakravarti, Rajes Ghosh, and Sudipta Sarkar | Constraining the topological Gauss-Bonnet coupling from GW150914 | Title and figure changed, table added. Manuscript has been modified
to match the published version in Physical Review D as a Letter. Main results
of the paper remains the same, although presentation has improved | Physical Review D 106, L041503 (2022) | 10.1103/PhysRevD.106.L041503 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent gravitational wave observation based on the data from GW150914 has
confirmed Hawking's area theorem and estimated the increase in total horizon
area during a merger process of two Kerr black holes. We use this result and
the validity of the second law to obtain the first observational bound on the
4D topological Gauss-Bonnet coupling as $\gamma \lesssim
2.804^{+7.946}_{-1.169} \times 10^{9}\, m^2$ with $95 \%$ credibility.
| [
{
"created": "Fri, 21 Jan 2022 13:54:07 GMT",
"version": "v1"
},
{
"created": "Mon, 15 Aug 2022 15:58:36 GMT",
"version": "v2"
}
] | 2022-08-16 | [
[
"Chakravarti",
"Kabir",
""
],
[
"Ghosh",
"Rajes",
""
],
[
"Sarkar",
"Sudipta",
""
]
] | Recent gravitational wave observation based on the data from GW150914 has confirmed Hawking's area theorem and estimated the increase in total horizon area during a merger process of two Kerr black holes. We use this result and the validity of the second law to obtain the first observational bound on the 4D topological Gauss-Bonnet coupling as $\gamma \lesssim 2.804^{+7.946}_{-1.169} \times 10^{9}\, m^2$ with $95 \%$ credibility. |
0709.0766 | Isabel Leonor | LIGO Scientific Collaboration | Search for Gravitational Waves Associated with 39 Gamma-Ray Bursts Using
Data from the Second, Third, and Fourth LIGO Runs | 24 pages, 10 figures, 14 tables; minor changes to text and Fig. 2;
accepted by Phys. Rev. D | Phys.Rev.D77:062004,2008 | 10.1103/PhysRevD.77.062004 | LIGO-P060024-07-Z | gr-qc astro-ph | null | We present the results of a search for short-duration gravitational-wave
bursts associated with 39 gamma-ray bursts (GRBs) detected by gamma-ray
satellite experiments during LIGO's S2, S3, and S4 science runs. The search
involves calculating the crosscorrelation between two interferometer data
streams surrounding the GRB trigger time. We search for associated
gravitational radiation from single GRBs, and also apply statistical tests to
search for a gravitational-wave signature associated with the whole sample. For
the sample examined, we find no evidence for the association of gravitational
radiation with GRBs, either on a single-GRB basis or on a statistical basis.
Simulating gravitational-wave bursts with sine-gaussian waveforms, we set upper
limits on the root-sum-square of the gravitational-wave strain amplitude of
such waveforms at the times of the GRB triggers. We also demonstrate how a
sample of several GRBs can be used collectively to set constraints on
population models. The small number of GRBs and the significant change in
sensitivity of the detectors over the three runs, however, limits the
usefulness of a population study for the S2, S3, and S4 runs. Finally, we
discuss prospects for the search sensitivity for the ongoing S5 run, and beyond
for the next generation of detectors.
| [
{
"created": "Thu, 6 Sep 2007 02:13:53 GMT",
"version": "v1"
},
{
"created": "Fri, 1 Feb 2008 19:35:42 GMT",
"version": "v2"
}
] | 2012-08-27 | [
[
"LIGO Scientific Collaboration",
"",
""
]
] | We present the results of a search for short-duration gravitational-wave bursts associated with 39 gamma-ray bursts (GRBs) detected by gamma-ray satellite experiments during LIGO's S2, S3, and S4 science runs. The search involves calculating the crosscorrelation between two interferometer data streams surrounding the GRB trigger time. We search for associated gravitational radiation from single GRBs, and also apply statistical tests to search for a gravitational-wave signature associated with the whole sample. For the sample examined, we find no evidence for the association of gravitational radiation with GRBs, either on a single-GRB basis or on a statistical basis. Simulating gravitational-wave bursts with sine-gaussian waveforms, we set upper limits on the root-sum-square of the gravitational-wave strain amplitude of such waveforms at the times of the GRB triggers. We also demonstrate how a sample of several GRBs can be used collectively to set constraints on population models. The small number of GRBs and the significant change in sensitivity of the detectors over the three runs, however, limits the usefulness of a population study for the S2, S3, and S4 runs. Finally, we discuss prospects for the search sensitivity for the ongoing S5 run, and beyond for the next generation of detectors. |
gr-qc/0411064 | Israel Quiros | Israel Quiros | Symmetry relating Gravity with Antigravity: A possible resolution of the
Cosmological Constant Problem? | 3 pages, no figures, revtex | null | null | null | gr-qc | null | I discuss possible implications a symmetry relating gravity with antigravity
might have for smoothing out of the cosmological constant puzzle. For this
purpose, a very simple model with spontaneous symmetry breaking is explored,
that is based on Einstein-Hilbert gravity with two self-interacting scalar
fields. The second (exotic) scalar particle with negative energy density, could
be interpreted, alternatively, as an antigravitating particle with positive
energy.
| [
{
"created": "Fri, 12 Nov 2004 21:24:07 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Quiros",
"Israel",
""
]
] | I discuss possible implications a symmetry relating gravity with antigravity might have for smoothing out of the cosmological constant puzzle. For this purpose, a very simple model with spontaneous symmetry breaking is explored, that is based on Einstein-Hilbert gravity with two self-interacting scalar fields. The second (exotic) scalar particle with negative energy density, could be interpreted, alternatively, as an antigravitating particle with positive energy. |
2006.16116 | Ashish Sharma | Ashish Sharma and Jan Harms | Searching for cosmological gravitational-wave backgrounds with
third-generation detectors in the presence of an astrophysical foreground | 11 pages, 10 figures | Phys. Rev. D 102, 063009 (2020) | 10.1103/PhysRevD.102.063009 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The stochastic cosmological gravitational-wave background (CGWB) provides a
direct window to study early universe phenomena and fundamental physics. With
the proposed third-generation ground-based gravitational wave detectors,
Einstein Telescope (ET) and Cosmic Explorer (CE), we might be able to detect
evidence of a CGWB. However, to dig out these prime signals would be a
difficult quest as the dominance of the astrophysical foreground from
compact-binary coalescence (CBC) will mask this CGWB. In this paper, we study a
subtraction-noise projection method, making it possible to reduce the residuals
left after subtraction of the astrophysical foreground of CBCs, greatly
improving our chances to detect a cosmological background. We carried out our
analysis based on simulations of ET and CE and using posterior sampling for the
parameter estimation of binary black-hole mergers. We demonstrate the
sensitivity improvement of stochastic gravitational-wave searches and conclude
that the ultimate sensitivity of these searches will not be limited by
residuals left when subtracting the estimated BBH foreground, but by the
fraction of the astrophysical foreground that cannot be detected even with
third-generation instruments, or possibly by other signals not included in our
analysis. We also resolve previous misconceptions of residual noise in the
context of Gaussian parameter estimation.
| [
{
"created": "Mon, 29 Jun 2020 15:25:24 GMT",
"version": "v1"
}
] | 2020-09-16 | [
[
"Sharma",
"Ashish",
""
],
[
"Harms",
"Jan",
""
]
] | The stochastic cosmological gravitational-wave background (CGWB) provides a direct window to study early universe phenomena and fundamental physics. With the proposed third-generation ground-based gravitational wave detectors, Einstein Telescope (ET) and Cosmic Explorer (CE), we might be able to detect evidence of a CGWB. However, to dig out these prime signals would be a difficult quest as the dominance of the astrophysical foreground from compact-binary coalescence (CBC) will mask this CGWB. In this paper, we study a subtraction-noise projection method, making it possible to reduce the residuals left after subtraction of the astrophysical foreground of CBCs, greatly improving our chances to detect a cosmological background. We carried out our analysis based on simulations of ET and CE and using posterior sampling for the parameter estimation of binary black-hole mergers. We demonstrate the sensitivity improvement of stochastic gravitational-wave searches and conclude that the ultimate sensitivity of these searches will not be limited by residuals left when subtracting the estimated BBH foreground, but by the fraction of the astrophysical foreground that cannot be detected even with third-generation instruments, or possibly by other signals not included in our analysis. We also resolve previous misconceptions of residual noise in the context of Gaussian parameter estimation. |
2109.14507 | Albert Much | Albert Much | A Deformation Quantization for Non-Flat Spacetimes and Applications to
QFT | Major revision | Journal of Physics A: Mathematical and Theoretical, 2024 | 10.1088/1751-8121/ad5b2f | null | gr-qc hep-th math-ph math.MP | http://creativecommons.org/licenses/by/4.0/ | We provide a deformation quantization, in the sense of Rieffel, for
\textit{all} globally hyperbolic spacetimes with a Poisson structure. The
Poisson structures have to satisfy Fedosov type requirements in order for the
deformed product to be associative. We apply the novel deformation to quantum
field theories and their respective states and we prove that the deformed state
(i.e.\ a state in non-commutative spacetime) has a singularity structure
resembling Minkowski, i.e.\ is \textit{Hadamard}, if the undeformed state is
Hadamard. This proves that the Hadamard condition, and hence the quantum field
theoretical implementation of the equivalence principle is a general concept
that holds in spacetimes with quantum features (i.e. a non-commutative
spacetime).
| [
{
"created": "Wed, 29 Sep 2021 15:42:54 GMT",
"version": "v1"
},
{
"created": "Fri, 6 May 2022 12:15:54 GMT",
"version": "v2"
},
{
"created": "Tue, 30 Jan 2024 13:20:12 GMT",
"version": "v3"
},
{
"created": "Thu, 4 Jul 2024 08:17:27 GMT",
"version": "v4"
}
] | 2024-07-08 | [
[
"Much",
"Albert",
""
]
] | We provide a deformation quantization, in the sense of Rieffel, for \textit{all} globally hyperbolic spacetimes with a Poisson structure. The Poisson structures have to satisfy Fedosov type requirements in order for the deformed product to be associative. We apply the novel deformation to quantum field theories and their respective states and we prove that the deformed state (i.e.\ a state in non-commutative spacetime) has a singularity structure resembling Minkowski, i.e.\ is \textit{Hadamard}, if the undeformed state is Hadamard. This proves that the Hadamard condition, and hence the quantum field theoretical implementation of the equivalence principle is a general concept that holds in spacetimes with quantum features (i.e. a non-commutative spacetime). |
1203.5592 | Julian Berengut | J. C. Berengut and V. V. Flambaum | Comment on "Global Positioning System Test of the Local Position
Invariance of Planck's Constant" | Reply to article available here: arXiv:1203.0102 | Phys. Rev. Lett. 109, 068901 (2012) | 10.1103/PhysRevLett.109.068901 | null | gr-qc astro-ph.CO hep-ph physics.atom-ph physics.space-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In their Letter, Kentosh and Mohageg [Phys. Rev. Lett. 108, 110801 (2012)]
seek to use data from clocks aboard global positioning system (GPS) satellites
to place limits on local position invariance (LPI) violations of Planck's
constant, h. It is the purpose of this comment to show that discussing limits
on variation of dimensional constants (such as h) is not meaningful; that even
within a correct framework it is not possible to extract limits on variation of
fundamental constants from a single type of clock aboard GPS satellites; and to
correct an important misconception in the authors' interpretation of previous
Earth-based LPI experiments.
| [
{
"created": "Mon, 26 Mar 2012 07:26:15 GMT",
"version": "v1"
}
] | 2012-09-11 | [
[
"Berengut",
"J. C.",
""
],
[
"Flambaum",
"V. V.",
""
]
] | In their Letter, Kentosh and Mohageg [Phys. Rev. Lett. 108, 110801 (2012)] seek to use data from clocks aboard global positioning system (GPS) satellites to place limits on local position invariance (LPI) violations of Planck's constant, h. It is the purpose of this comment to show that discussing limits on variation of dimensional constants (such as h) is not meaningful; that even within a correct framework it is not possible to extract limits on variation of fundamental constants from a single type of clock aboard GPS satellites; and to correct an important misconception in the authors' interpretation of previous Earth-based LPI experiments. |
2102.05391 | Wen-Biao Han | Chen Zhang, Wen-Biao Han, Xing-Yu Zhong, Gang Wang | Geometrized effective-one-body formalism for extreme-mass-ratio limits:
Generic orbits | 22 pages, 18figures | Phys. Rev. D 104, 024050 (2021) | 10.1103/PhysRevD.104.024050 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Compact objects inspiraling into supermassive black holes, known as
extreme-mass-ratio inspirals, are an important source for future space-borne
gravitational-wave detectors. When constructing waveform templates, usually the
adiabatic approximation is employed to treat the compact object as a test
particle for a short duration, and the radiation reaction is reflected in the
changes of the constants of motion. However, the mass of the compact object
should have contributions to the background. In the present paper, employing
the effective-one-body formalism, we analytically calculate the trajectories of
a compact object around a massive Kerr black hole with generally
three-dimensional orbits and express the fundamental orbital frequencies in
explicit forms. In addition, by constructing an approximate "constant" similar
to the Carter constant, we transfer the dynamical quantities such as energy,
angular momentum, and the "Carter constant" to the semilatus rectum,
eccentricity, and orbital inclination with mass-ratio corrections. The linear
mass-ratio terms in the formalism may not be sufficient for accurate waveforms,
but our analytical method for solving the equations of motion could be useful
in various approaches to building waveform models.
| [
{
"created": "Wed, 10 Feb 2021 11:45:43 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Jul 2021 15:36:09 GMT",
"version": "v2"
}
] | 2021-08-04 | [
[
"Zhang",
"Chen",
""
],
[
"Han",
"Wen-Biao",
""
],
[
"Zhong",
"Xing-Yu",
""
],
[
"Wang",
"Gang",
""
]
] | Compact objects inspiraling into supermassive black holes, known as extreme-mass-ratio inspirals, are an important source for future space-borne gravitational-wave detectors. When constructing waveform templates, usually the adiabatic approximation is employed to treat the compact object as a test particle for a short duration, and the radiation reaction is reflected in the changes of the constants of motion. However, the mass of the compact object should have contributions to the background. In the present paper, employing the effective-one-body formalism, we analytically calculate the trajectories of a compact object around a massive Kerr black hole with generally three-dimensional orbits and express the fundamental orbital frequencies in explicit forms. In addition, by constructing an approximate "constant" similar to the Carter constant, we transfer the dynamical quantities such as energy, angular momentum, and the "Carter constant" to the semilatus rectum, eccentricity, and orbital inclination with mass-ratio corrections. The linear mass-ratio terms in the formalism may not be sufficient for accurate waveforms, but our analytical method for solving the equations of motion could be useful in various approaches to building waveform models. |
1110.2938 | Alessandro Nagar | Thibault Damour, Alessandro Nagar, Denis Pollney, Christian Reisswig | Energy versus Angular Momentum in Black Hole Binaries | 4 pages, 2 figures | null | 10.1103/PhysRevLett.108.131101 | null | gr-qc astro-ph.HE | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Using accurate numerical relativity simulations of (nonspinning) black-hole
binaries with mass ratios 1:1, 2:1 and 3:1 we compute the gauge invariant
relation between the (reduced) binding energy $E$ and the (reduced) angular
momentum $j$ of the system. We show that the relation $E(j)$ is an accurate
diagnostic of the dynamics of a black-hole binary in a highly relativistic
regime. By comparing the numerical-relativity $E^{\rm NR} (j)$ curve with the
predictions of several analytic approximation schemes, we find that, while the
usual, non-resummed post-Newtonian-expanded $E^{\rm PN} (j)$ relation exhibits
large and growing deviations from $E^{\rm NR} (j)$, the prediction of the
effective one-body formalism, based purely on known analytical results (without
any calibration to numerical relativity), agrees strikingly well with the
numerical-relativity results.
| [
{
"created": "Thu, 13 Oct 2011 13:34:34 GMT",
"version": "v1"
}
] | 2015-05-30 | [
[
"Damour",
"Thibault",
""
],
[
"Nagar",
"Alessandro",
""
],
[
"Pollney",
"Denis",
""
],
[
"Reisswig",
"Christian",
""
]
] | Using accurate numerical relativity simulations of (nonspinning) black-hole binaries with mass ratios 1:1, 2:1 and 3:1 we compute the gauge invariant relation between the (reduced) binding energy $E$ and the (reduced) angular momentum $j$ of the system. We show that the relation $E(j)$ is an accurate diagnostic of the dynamics of a black-hole binary in a highly relativistic regime. By comparing the numerical-relativity $E^{\rm NR} (j)$ curve with the predictions of several analytic approximation schemes, we find that, while the usual, non-resummed post-Newtonian-expanded $E^{\rm PN} (j)$ relation exhibits large and growing deviations from $E^{\rm NR} (j)$, the prediction of the effective one-body formalism, based purely on known analytical results (without any calibration to numerical relativity), agrees strikingly well with the numerical-relativity results. |
1012.2108 | Roldao da Rocha | J M Hoff da Silva, Roldao da Rocha | Possible Generalizations within Braneworld Scenarios: Torsion fields | 21 pages, to be published as Chapter of "Classical and Quantum
Gravity: Theory, Analysis and Applications" | "Classical and Quantum Gravity: Theory, Analysis and Applications"
(Nova Science Publ., Inc.), 1, 477-506 (2011) | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this Chapter we introduce the aspects in which torsion can influence the
formalism of braneworld scenarios in general, and also how it is possible to
measure such kind of effects, namely, for instance, the blackstring transverse
area corrections and variation of quasar luminosity due to those corrections.
We analyze the projected effective Einstein equation in a 4-dimensional
arbitrary manifold embedded in a 5-dimensional Riemann-Cartan manifold. The
Israel-Darmois matching conditions are investigated, in the context where the
torsion discontinuity is orthogonal to the brane. Unexpectedly, the presence of
torsion terms in the connection does not modify such conditions whatsoever,
despite of the modification in the extrinsic curvature and in the connection.
Then, by imposing the Z2-symmetry, the Einstein equation obtained via
Gauss-Codazzi formalism is extended, in order to now encompass the torsion
terms. We also show that the factors involving contorsion change drastically
the effective Einstein equation on the brane, as well as the effective
cosmological constant. Also, we present gravitational aspects of braneworld
models endowed with torsion terms both in the bulk and on the brane. In order
to investigate a conceivable and measurable gravitational effect, arising
genuinely from bulk torsion terms, we analyze the variation in the black hole
area by the presence of torsion. Furthermore, we extend the well known results
about consistency conditions in a framework that incorporates brane torsion
terms. It is shown, in a rough estimate, that the resulting effects are
generally suppressed by the internal space volume.
| [
{
"created": "Thu, 9 Dec 2010 20:43:55 GMT",
"version": "v1"
}
] | 2012-03-13 | [
[
"da Silva",
"J M Hoff",
""
],
[
"da Rocha",
"Roldao",
""
]
] | In this Chapter we introduce the aspects in which torsion can influence the formalism of braneworld scenarios in general, and also how it is possible to measure such kind of effects, namely, for instance, the blackstring transverse area corrections and variation of quasar luminosity due to those corrections. We analyze the projected effective Einstein equation in a 4-dimensional arbitrary manifold embedded in a 5-dimensional Riemann-Cartan manifold. The Israel-Darmois matching conditions are investigated, in the context where the torsion discontinuity is orthogonal to the brane. Unexpectedly, the presence of torsion terms in the connection does not modify such conditions whatsoever, despite of the modification in the extrinsic curvature and in the connection. Then, by imposing the Z2-symmetry, the Einstein equation obtained via Gauss-Codazzi formalism is extended, in order to now encompass the torsion terms. We also show that the factors involving contorsion change drastically the effective Einstein equation on the brane, as well as the effective cosmological constant. Also, we present gravitational aspects of braneworld models endowed with torsion terms both in the bulk and on the brane. In order to investigate a conceivable and measurable gravitational effect, arising genuinely from bulk torsion terms, we analyze the variation in the black hole area by the presence of torsion. Furthermore, we extend the well known results about consistency conditions in a framework that incorporates brane torsion terms. It is shown, in a rough estimate, that the resulting effects are generally suppressed by the internal space volume. |
gr-qc/0407063 | Jose Luis Jaramillo | J.L. Jaramillo, E. Gourgoulhon, G.A. Mena Marugan | Inner boundary conditions for black hole Initial Data derived from
Isolated Horizons | 13 pages. Major general revision. Section V comparing with previous
approaches restructured; discussion on the lapse boundary condition extended.
Appendix with some technical details added. Version accepted for publication
in Phys.Rev.D | Phys.Rev. D70 (2004) 124036 | 10.1103/PhysRevD.70.124036 | null | gr-qc | null | We present a set of boundary conditions for solving the elliptic equations in
the Initial Data Problem for space-times containing a black hole, together with
a number of constraints to be satisfied by the otherwise freely specifiable
standard parameters of the Conformal Thin Sandwich formulation. These
conditions altogether are sufficient for the construction of a horizon that is
instantaneously in equilibrium in the sense of the Isolated Horizons formalism.
We then investigate the application of these conditions to the Initial Data
Problem of binary black holes and discuss the relation of our analysis with
other proposals that exist in the literature.
| [
{
"created": "Fri, 16 Jul 2004 10:23:13 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Nov 2004 18:38:29 GMT",
"version": "v2"
}
] | 2009-11-10 | [
[
"Jaramillo",
"J. L.",
""
],
[
"Gourgoulhon",
"E.",
""
],
[
"Marugan",
"G. A. Mena",
""
]
] | We present a set of boundary conditions for solving the elliptic equations in the Initial Data Problem for space-times containing a black hole, together with a number of constraints to be satisfied by the otherwise freely specifiable standard parameters of the Conformal Thin Sandwich formulation. These conditions altogether are sufficient for the construction of a horizon that is instantaneously in equilibrium in the sense of the Isolated Horizons formalism. We then investigate the application of these conditions to the Initial Data Problem of binary black holes and discuss the relation of our analysis with other proposals that exist in the literature. |
gr-qc/0312031 | Duncan Brown | Duncan A. Brown (for the LIGO Scientific Collaboration) | Testing the LIGO Inspiral Analysis with Hardware Injections | 6 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo
Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July
2003 | Class.Quant.Grav. 21 (2004) S797-S800 | null | null | gr-qc | null | Injection of simulated binary inspiral signals into detector hardware
provides an excellent test of the inspiral detection pipeline. By recovering
the physical parameters of an injected signal, we test our understanding of
both instrumental calibration and the data analysis pipeline. We describe an
inspiral search code and results from hardware injection tests and demonstrate
that injected signals can be recovered by the data analysis pipeline. The
parameters of the recovered signals match those of the injected signals.
| [
{
"created": "Thu, 4 Dec 2003 18:20:52 GMT",
"version": "v1"
}
] | 2019-08-14 | [
[
"Brown",
"Duncan A.",
"",
"for the LIGO Scientific Collaboration"
]
] | Injection of simulated binary inspiral signals into detector hardware provides an excellent test of the inspiral detection pipeline. By recovering the physical parameters of an injected signal, we test our understanding of both instrumental calibration and the data analysis pipeline. We describe an inspiral search code and results from hardware injection tests and demonstrate that injected signals can be recovered by the data analysis pipeline. The parameters of the recovered signals match those of the injected signals. |
gr-qc/9904079 | Roman R. Zapatrin | Ioannis Raptis and Roman R. Zapatrin | Quantization of discretized spacetimes and the correspondence principle | 15 pages, no figures, LaTeX 2.09 | Int.J.Theor.Phys. 39 (2000) 1-13 | null | null | gr-qc math-ph math.MP quant-ph | null | An algebraic quantization procedure for discretized spacetime models is
suggested based on the duality between finitary substitutes and their incidence
algebras. The provided limiting procedure that yields conventional manifold
characteristics of spacetime structures is interpreted in the algebraic quantum
framework as a correspondence principle.
| [
{
"created": "Thu, 29 Apr 1999 14:30:16 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Raptis",
"Ioannis",
""
],
[
"Zapatrin",
"Roman R.",
""
]
] | An algebraic quantization procedure for discretized spacetime models is suggested based on the duality between finitary substitutes and their incidence algebras. The provided limiting procedure that yields conventional manifold characteristics of spacetime structures is interpreted in the algebraic quantum framework as a correspondence principle. |
2402.02919 | Andronikos Paliathanasis | Andronikos Paliathanasis | Attractors in $f(Q,B)$-gravity | 22 pages, 4 figures, title changed, to appear in Physics of Dark
Universe | null | null | null | gr-qc hep-ph | http://creativecommons.org/licenses/by/4.0/ | We investigate the asymptotic behavior of the cosmological field equations in
Symmetric Teleparallel General Relativity, where a nonlinear function of the
boundary term is introduced instead of the cosmological constant to describe
the acceleration phase of the universe. Our analysis reveals constraints on the
free parameters necessary for the existence of an attractor that accurately
represents acceleration. However, we also identify asymptotic solutions
depicting Big Rip and Big Crunch singularities. To avoid these solutions, we
must impose constraints on the phase-space, requiring specific initial
conditions.
| [
{
"created": "Mon, 5 Feb 2024 11:38:33 GMT",
"version": "v1"
},
{
"created": "Tue, 7 May 2024 05:16:33 GMT",
"version": "v2"
}
] | 2024-05-08 | [
[
"Paliathanasis",
"Andronikos",
""
]
] | We investigate the asymptotic behavior of the cosmological field equations in Symmetric Teleparallel General Relativity, where a nonlinear function of the boundary term is introduced instead of the cosmological constant to describe the acceleration phase of the universe. Our analysis reveals constraints on the free parameters necessary for the existence of an attractor that accurately represents acceleration. However, we also identify asymptotic solutions depicting Big Rip and Big Crunch singularities. To avoid these solutions, we must impose constraints on the phase-space, requiring specific initial conditions. |
gr-qc/0102035 | Robert T. Jantzen | Robert T. Jantzen | Spatially Homogeneous Dynamics: A Unified Picture | 84 pages in latex(2e) article style with 10 encapsulated postscript
figures, uses graphics package; reformatted with corrections from
out-of-print book Proc. Int. Sch. Phys. "E. Fermi" Course LXXXVI (1982) on
"Gamov Cosmology" (R. Ruffini, F. Melchiorri, Eds.), North Holland,
Amsterdam, 1987, 61-147; resurrected from behind the "literature horizon" | null | null | null | gr-qc | null | The Einstein equations for a perfect fluid spatially homogeneous spacetime
are studied in a unified manner by retaining the generality of certain
parameters whose discrete values correspond to the various Bianchi types of
spatial homogeneity. A parameter-dependent decomposition of the metric
variables adapted to the symmetry breaking effects of the nonabelian Bianchi
types on the "free dynamics" leads to a reduction of the equations of motion
for those variables to a 2-dimensional time-dependent Hamiltonian system
containing various time-dependent potentials which are explicitly described and
diagrammed. These potentials are extremely useful in deducing the gross
features of the evolution of the metric variables.
| [
{
"created": "Thu, 8 Feb 2001 23:31:28 GMT",
"version": "v1"
},
{
"created": "Mon, 12 Feb 2001 22:55:15 GMT",
"version": "v2"
}
] | 2007-05-23 | [
[
"Jantzen",
"Robert T.",
""
]
] | The Einstein equations for a perfect fluid spatially homogeneous spacetime are studied in a unified manner by retaining the generality of certain parameters whose discrete values correspond to the various Bianchi types of spatial homogeneity. A parameter-dependent decomposition of the metric variables adapted to the symmetry breaking effects of the nonabelian Bianchi types on the "free dynamics" leads to a reduction of the equations of motion for those variables to a 2-dimensional time-dependent Hamiltonian system containing various time-dependent potentials which are explicitly described and diagrammed. These potentials are extremely useful in deducing the gross features of the evolution of the metric variables. |
2408.02755 | Philip Beltracchi | Philip Beltracchi | Simple Bianchi cosmologies with anisotropic Segre [1(11,1)] dark energy | null | null | null | null | gr-qc astro-ph.CO | http://creativecommons.org/licenses/by/4.0/ | In this paper, we use a sample anisotropic but spatially homogeneous metric
to look at the properties of Segre type [1(11,1)] universes, that behave like
vacuum energy along a spatial plane (two stresses equal to the negative
density) but have distinct stress along the third spatial axis. We examine
situations with simple relationships between the distinct and degenerate
stresses, finding a closed form parameterizations for the case where the
distinct stress is equal to zero and finding new conditions in which the case
with all stresses equal has a closed form parameterization. We also use
numerical methods to illustrate possible behaviors for the case where the
distinct stress is the negative of the degenerate stresses.
| [
{
"created": "Mon, 5 Aug 2024 18:18:36 GMT",
"version": "v1"
}
] | 2024-08-07 | [
[
"Beltracchi",
"Philip",
""
]
] | In this paper, we use a sample anisotropic but spatially homogeneous metric to look at the properties of Segre type [1(11,1)] universes, that behave like vacuum energy along a spatial plane (two stresses equal to the negative density) but have distinct stress along the third spatial axis. We examine situations with simple relationships between the distinct and degenerate stresses, finding a closed form parameterizations for the case where the distinct stress is equal to zero and finding new conditions in which the case with all stresses equal has a closed form parameterization. We also use numerical methods to illustrate possible behaviors for the case where the distinct stress is the negative of the degenerate stresses. |
2111.06255 | Manuel Hohmann | Manuel Hohmann | Gauge-invariant post-Newtonian perturbations in symmetric teleparallel
gravity | Paper presented at the Fourth Zeldovich meeting, an international
conference in honor of Ya. B. Zeldovich held in Minsk, Belarus on September
7--11, 2020. Published by the recommendation of the special editors: S. Ya.
Kilin, R. Ruffini and G. V. Vereshchagin | Astron. Rep. 65 (2021) 952 | 10.1134/S1063772921100140 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present an extension to the gauge-invariant formulation of the
parameterized post-Newtonian (PPN) formalism, which allows its application to
symmetric teleparallel gravity theories. In its original formulation, the
gauge-invariant PPN formalism makes use of a gauge-invariant perturbative
expansion of tensor fields; however, one of the fundamental gravitational field
variables in symmetric teleparallel gravity theories is a flat, torsion-free
connection, hence not a tensor field. Since connections transform differently
from tensor fields under diffeomorphisms, we introduce here an adapted notion
of gauge-invariant perturbation variables for the symmetric teleparallel
connection, and show how the lowest order terms can be expressed in terms of
the common PPN potentials.
| [
{
"created": "Thu, 4 Nov 2021 16:09:44 GMT",
"version": "v1"
}
] | 2021-11-12 | [
[
"Hohmann",
"Manuel",
""
]
] | We present an extension to the gauge-invariant formulation of the parameterized post-Newtonian (PPN) formalism, which allows its application to symmetric teleparallel gravity theories. In its original formulation, the gauge-invariant PPN formalism makes use of a gauge-invariant perturbative expansion of tensor fields; however, one of the fundamental gravitational field variables in symmetric teleparallel gravity theories is a flat, torsion-free connection, hence not a tensor field. Since connections transform differently from tensor fields under diffeomorphisms, we introduce here an adapted notion of gauge-invariant perturbation variables for the symmetric teleparallel connection, and show how the lowest order terms can be expressed in terms of the common PPN potentials. |
gr-qc/0411012 | Golam Mortuza Hossain | Golam Mortuza Hossain | Primordial Density Perturbation in Effective Loop Quantum Cosmology | 33 pages, revtex4, few typos and a confusing notation changed;
several clarifications, references added, to appear in CQG | Class.Quant.Grav.22:2511-2532,2005 | 10.1088/0264-9381/22/12/012 | IMSc/2004/11/37; AEI-2004-100 | gr-qc astro-ph hep-th | null | It is widely believed that quantum field fluctuation in an inflating
background creates the primeval seed perturbation which through subsequent
evolution leads to the observed large scale structure of the universe. The
standard inflationary scenario produces scale invariant power spectrum quite
generically but it produces, unless fine tuned, too large amplitude for the
primordial density perturbation than observed. Using similar techniques it is
shown that loop quantum cosmology induced inflationary scenario can produce
scale invariant power spectrum as well as small amplitude for the primordial
density perturbation without fine tuning. Further its power spectrum has a
qualitatively distinct feature which is in principle falsifiable by observation
and can distinguish it from the standard inflationary scenario.
| [
{
"created": "Mon, 1 Nov 2004 18:12:02 GMT",
"version": "v1"
},
{
"created": "Thu, 4 Nov 2004 05:10:07 GMT",
"version": "v2"
},
{
"created": "Mon, 9 May 2005 05:02:56 GMT",
"version": "v3"
}
] | 2010-11-05 | [
[
"Hossain",
"Golam Mortuza",
""
]
] | It is widely believed that quantum field fluctuation in an inflating background creates the primeval seed perturbation which through subsequent evolution leads to the observed large scale structure of the universe. The standard inflationary scenario produces scale invariant power spectrum quite generically but it produces, unless fine tuned, too large amplitude for the primordial density perturbation than observed. Using similar techniques it is shown that loop quantum cosmology induced inflationary scenario can produce scale invariant power spectrum as well as small amplitude for the primordial density perturbation without fine tuning. Further its power spectrum has a qualitatively distinct feature which is in principle falsifiable by observation and can distinguish it from the standard inflationary scenario. |
gr-qc/0106088 | Nils Andersson | K. H. Lockitch, N. Andersson and A.L. Watts | Regularizing the r-mode problem for nonbarotropic relativistic stars | considerably revised version, to appear in Class. Quantum. Grav | Class.Quant.Grav. 21 (2004) 4661-4676 | 10.1088/0264-9381/21/19/012 | null | gr-qc | null | We present results for r-modes of relativistic nonbarotropic stars. We show
that the main differential equation, which is formally singular at lowest order
in the slow-rotation expansion, can be regularized if one considers the initial
value problem rather than the normal mode problem. However, a more physically
motivated way to regularize the problem is to include higher order terms. This
allows us to develop a practical approach for solving the problem and we
provide results that support earlier conclusions obtained for uniform density
stars. In particular, we show that there will exist a single r-mode for each
permissible combination of $l$ and $m$. We discuss these results and provide
some caveats regarding their usefulness for estimates of
gravitational-radiation reaction timescales. The close connection between the
seemingly singular relativistic r-mode problem and issues arising because of
the presence of corotation points in differentially rotating stars is also
clarified.
| [
{
"created": "Wed, 27 Jun 2001 17:28:40 GMT",
"version": "v1"
},
{
"created": "Fri, 10 Sep 2004 14:38:25 GMT",
"version": "v2"
}
] | 2009-11-07 | [
[
"Lockitch",
"K. H.",
""
],
[
"Andersson",
"N.",
""
],
[
"Watts",
"A. L.",
""
]
] | We present results for r-modes of relativistic nonbarotropic stars. We show that the main differential equation, which is formally singular at lowest order in the slow-rotation expansion, can be regularized if one considers the initial value problem rather than the normal mode problem. However, a more physically motivated way to regularize the problem is to include higher order terms. This allows us to develop a practical approach for solving the problem and we provide results that support earlier conclusions obtained for uniform density stars. In particular, we show that there will exist a single r-mode for each permissible combination of $l$ and $m$. We discuss these results and provide some caveats regarding their usefulness for estimates of gravitational-radiation reaction timescales. The close connection between the seemingly singular relativistic r-mode problem and issues arising because of the presence of corotation points in differentially rotating stars is also clarified. |
1909.10049 | Pavel Friedrich | Pavel Friedrich and Tomislav Prokopec | Field-theoretic approach to large-scale structure formation | accepted for publication in PRD | Phys. Rev. D 100, 103527 (2019) | 10.1103/PhysRevD.100.103527 | null | gr-qc astro-ph.CO hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We develop a field-theoretic description of large-scale structure formation
by taking the non-relativistic limit of a canonically transformed, real scalar
field which is minimally coupled to scalar gravitational perturbations in
longitudinal gauge. We integrate out the gravitational constraint fields and
arrive at a non-local action which is only specified in terms of the dynamical
degrees of freedom. In order to make this framework closer to the classical
particle description, we construct the corresponding 2PI effective action
truncated at two loop order for a non-squeezed state without field expectation
values. We contrast the dynamical description of the coincident time
phase-space density to the standard Vlasov description of cold dark matter
particles and identify momentum and time scales at which linear perturbation
theory will deviate from the standard evolution.
| [
{
"created": "Sun, 22 Sep 2019 17:27:15 GMT",
"version": "v1"
},
{
"created": "Thu, 7 Nov 2019 14:46:42 GMT",
"version": "v2"
}
] | 2019-12-04 | [
[
"Friedrich",
"Pavel",
""
],
[
"Prokopec",
"Tomislav",
""
]
] | We develop a field-theoretic description of large-scale structure formation by taking the non-relativistic limit of a canonically transformed, real scalar field which is minimally coupled to scalar gravitational perturbations in longitudinal gauge. We integrate out the gravitational constraint fields and arrive at a non-local action which is only specified in terms of the dynamical degrees of freedom. In order to make this framework closer to the classical particle description, we construct the corresponding 2PI effective action truncated at two loop order for a non-squeezed state without field expectation values. We contrast the dynamical description of the coincident time phase-space density to the standard Vlasov description of cold dark matter particles and identify momentum and time scales at which linear perturbation theory will deviate from the standard evolution. |
2112.02426 | Swapnil Nitin Shah | Swapnil Nitin Shah | Quantum Simulations of Loop Quantum Gravity | 7 pages, 6 figures | null | null | null | gr-qc quant-ph | http://creativecommons.org/licenses/by/4.0/ | Loop Quantum Gravity (LQG) is one of the leading approaches to unify quantum
physics and General Relativity (GR). The Hilbert space of LQG is spanned by
spin-networks which describe the local geometry of quantum space-time.
Simulation of LQG spin-network states and their dynamics is classically
intractable and is widely believed to fall in the Bounded Quantum Polynomial
(BQP) time complexity class. There have been many recent attempts to simulate
these states using novel and off the shelf quantum computing technologies. In
this article, we review three such efforts which utilize superconducting
qubits, linear optical qubits and Nuclear Magnetic Resonance (NMR) qubits
respectively. The articles chosen for this review represent state of the art in
quantum simulations of LQG.
| [
{
"created": "Sat, 4 Dec 2021 20:40:03 GMT",
"version": "v1"
},
{
"created": "Mon, 20 Dec 2021 02:54:16 GMT",
"version": "v2"
}
] | 2021-12-21 | [
[
"Shah",
"Swapnil Nitin",
""
]
] | Loop Quantum Gravity (LQG) is one of the leading approaches to unify quantum physics and General Relativity (GR). The Hilbert space of LQG is spanned by spin-networks which describe the local geometry of quantum space-time. Simulation of LQG spin-network states and their dynamics is classically intractable and is widely believed to fall in the Bounded Quantum Polynomial (BQP) time complexity class. There have been many recent attempts to simulate these states using novel and off the shelf quantum computing technologies. In this article, we review three such efforts which utilize superconducting qubits, linear optical qubits and Nuclear Magnetic Resonance (NMR) qubits respectively. The articles chosen for this review represent state of the art in quantum simulations of LQG. |
2305.15350 | Jose Miguel Ladino | Jose Miguel Ladino, Carlos A. Benavides-Gallego, Eduard Larra\~naga,
Javlon Rayimbaev and Farrux Abdulxamidov | Charged spinning and magnetized test particles orbiting quantum improved
charged black holes | 16 pages, 12 figures, 1 table | Eur. Phys. J. C 83, 989 (2023) | 10.1140/epjc/s10052-023-12187-2 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present work, we aimed to investigate the dynamics of spinning charged
and magnetized test particles around both electrically and magnetically charged
quantum-improved black holes. We derive the equations of motion for charged
spinning test particles using the Mathisson-Papapetrou-Dixon equations with the
Lorentz coupling term. The radius of innermost stable circular orbits (ISCOs),
specific angular momentum, and energy for charged spinless, uncharged spinning,
and charged spinning test particles around the charged and non-charged
quantum-improved black holes are analyzed separately. We found that the quantum
parameter increases the maximum spin value, $s_\text{max}$, which leads to the
nonphysical motion (superluminal motion) of the charged spinning test particle,
whereas the black hole charge decreases its value. We also found that, in
contrast to the Reissner Nordstr\"om black hole, spinning charged test
particles in the quantum-improved charged black hole have higher
$s_\text{max}$; moreover, positively charged spinning particles can have higher
values of $s_\text{max}$ near the extreme black hole cases when compared with
uncharged spinning particles. Finally, we investigate the magnetized test
particle's dynamics around a quantum-improved magnetically charged black hole
in Quantum Einstein Gravity using the Hamilton-Jacobi equation. We show that
the presence of $\omega$ increases the maximum value of the effective potential
and decreases the minimum energy and angular momentum of magnetized particles
at their circular orbits. We found an upper constraint in the black hole charge
at the ISCO.
| [
{
"created": "Wed, 24 May 2023 17:00:39 GMT",
"version": "v1"
}
] | 2023-11-07 | [
[
"Ladino",
"Jose Miguel",
""
],
[
"Benavides-Gallego",
"Carlos A.",
""
],
[
"Larrañaga",
"Eduard",
""
],
[
"Rayimbaev",
"Javlon",
""
],
[
"Abdulxamidov",
"Farrux",
""
]
] | In the present work, we aimed to investigate the dynamics of spinning charged and magnetized test particles around both electrically and magnetically charged quantum-improved black holes. We derive the equations of motion for charged spinning test particles using the Mathisson-Papapetrou-Dixon equations with the Lorentz coupling term. The radius of innermost stable circular orbits (ISCOs), specific angular momentum, and energy for charged spinless, uncharged spinning, and charged spinning test particles around the charged and non-charged quantum-improved black holes are analyzed separately. We found that the quantum parameter increases the maximum spin value, $s_\text{max}$, which leads to the nonphysical motion (superluminal motion) of the charged spinning test particle, whereas the black hole charge decreases its value. We also found that, in contrast to the Reissner Nordstr\"om black hole, spinning charged test particles in the quantum-improved charged black hole have higher $s_\text{max}$; moreover, positively charged spinning particles can have higher values of $s_\text{max}$ near the extreme black hole cases when compared with uncharged spinning particles. Finally, we investigate the magnetized test particle's dynamics around a quantum-improved magnetically charged black hole in Quantum Einstein Gravity using the Hamilton-Jacobi equation. We show that the presence of $\omega$ increases the maximum value of the effective potential and decreases the minimum energy and angular momentum of magnetized particles at their circular orbits. We found an upper constraint in the black hole charge at the ISCO. |
2106.02536 | Peter Cameron | Peter Cameron | The Penrose Property with a Cosmological Constant | null | Class. Quantum Grav. 39 115002 (2022) | 10.1088/1361-6382/ac66b7 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A spacetime satisfies the non-timelike boundary version of the Penrose
property if the timelike future of any point on $\mathcal{I}^-$ contains the
whole of $\mathcal{I}^+$. This property was first discussed for asymptotically
flat spacetimes by Penrose, along with an equivalent definition (the finite
version). In this paper we consider the Penrose property in greater generality.
In particular we consider spacetimes with a non-zero cosmological constant and
we note that the two versions of the property are no longer equivalent. In
asymptotically AdS spacetimes it is necessary to re-state the property in a way
which is more suited to spacetimes with a timelike boundary. We arrive at a
property previously considered by Gao and Wald. Curiously, this property was
shown to fail in spacetimes which focus null geodesics. This is in contrast to
our findings in asymptotically flat and asymptotically de Sitter spacetimes. We
then move on to consider some further example spacetimes (with zero
cosmological constant) which highlight features of the Penrose property not
previously considered. We discuss spacetimes which are the product of a
Lorentzian and a compact Riemannian manifold. Perhaps surprisingly, we find
that both versions of the Penrose property are satisfied in this product
spacetime if and only if they are satisfied in the Lorentzian spacetime only.
We also discuss the Ellis-Bronnikov wormhole (an example of a spacetime with
more than one asymptotically flat end) and the Hayward metric (an example of a
non-singular black hole spacetime).
| [
{
"created": "Fri, 4 Jun 2021 15:04:41 GMT",
"version": "v1"
},
{
"created": "Thu, 5 May 2022 08:32:28 GMT",
"version": "v2"
}
] | 2023-11-21 | [
[
"Cameron",
"Peter",
""
]
] | A spacetime satisfies the non-timelike boundary version of the Penrose property if the timelike future of any point on $\mathcal{I}^-$ contains the whole of $\mathcal{I}^+$. This property was first discussed for asymptotically flat spacetimes by Penrose, along with an equivalent definition (the finite version). In this paper we consider the Penrose property in greater generality. In particular we consider spacetimes with a non-zero cosmological constant and we note that the two versions of the property are no longer equivalent. In asymptotically AdS spacetimes it is necessary to re-state the property in a way which is more suited to spacetimes with a timelike boundary. We arrive at a property previously considered by Gao and Wald. Curiously, this property was shown to fail in spacetimes which focus null geodesics. This is in contrast to our findings in asymptotically flat and asymptotically de Sitter spacetimes. We then move on to consider some further example spacetimes (with zero cosmological constant) which highlight features of the Penrose property not previously considered. We discuss spacetimes which are the product of a Lorentzian and a compact Riemannian manifold. Perhaps surprisingly, we find that both versions of the Penrose property are satisfied in this product spacetime if and only if they are satisfied in the Lorentzian spacetime only. We also discuss the Ellis-Bronnikov wormhole (an example of a spacetime with more than one asymptotically flat end) and the Hayward metric (an example of a non-singular black hole spacetime). |
1610.04277 | Iarley P. Lobo Mr | Iarley P. Lobo, Niccol\'o Loret and Francisco Nettel | Rainbows without unicorns: Metric structures in theories with Modified
Dispersion Relations | 10 pages. Discussion on the role of connections was added. Matches
published version | Eur. Phys. J. C (2017) 77:451 | 10.1140/epjc/s10052-017-5017-0 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Rainbow metrics are a widely used approach to metric formalism for theories
with Modified Dispersion Relations. They have had a huge success in the Quantum
Gravity Phenomenology literature, since they allow to introduce
momentum-dependent spacetime metrics into the description of systems with
Modified Dispersion Relation. In this paper, we introduce the reader to some
realizations of this general idea: the original Rainbow metrics proposal, the
momentum-space-inspired metric, the standard Finsler geometry approach and our
alternative definition of a four-velocity-dependent metric with a massless
limit. This paper aims to highlight some of their properties and how to
properly describe their relativistic realizations.
| [
{
"created": "Thu, 13 Oct 2016 22:07:50 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Feb 2017 09:32:21 GMT",
"version": "v2"
},
{
"created": "Sun, 9 Jul 2017 18:15:59 GMT",
"version": "v3"
}
] | 2017-07-11 | [
[
"Lobo",
"Iarley P.",
""
],
[
"Loret",
"Niccoló",
""
],
[
"Nettel",
"Francisco",
""
]
] | Rainbow metrics are a widely used approach to metric formalism for theories with Modified Dispersion Relations. They have had a huge success in the Quantum Gravity Phenomenology literature, since they allow to introduce momentum-dependent spacetime metrics into the description of systems with Modified Dispersion Relation. In this paper, we introduce the reader to some realizations of this general idea: the original Rainbow metrics proposal, the momentum-space-inspired metric, the standard Finsler geometry approach and our alternative definition of a four-velocity-dependent metric with a massless limit. This paper aims to highlight some of their properties and how to properly describe their relativistic realizations. |
1103.4005 | Martin Kolo\v{s} | Martin Kolo\v{s}, Zden\v{e}k Stuchl\'ik | Current-carrying string loops in black-hole spacetimes with a repulsive
cosmological constant | 21 pages, 22 figures | Phys.Rev.D82:125012,2010 | 10.1103/PhysRevD.82.125012 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Current-carrying string loop dynamics in Schwarzschild-de Sitter spacetimes
characterized by the cosmological parameter {\lambda}=1/3{\Lambda}M^2 is
investigated. With attention concentrated to the axisymmetric motion of string
loops it is shown that the resulting motion is governed by the presence of an
outer tension barrier and an inner angular momentum barrier that are influenced
by the black hole gravitational field given by the mass M and the cosmic
repulsion given by the cosmological constant {\Lambda}. The gravitational
attraction could cause capturing of the string having low energy by the black
hole or trapping in its vicinity; with high enough energy, the string can
escape (scatter) to infinity. The role of the cosmic repulsion becomes
important in vicinity of the so-called static radius where the gravitational
attraction is balanced by the cosmic repulsion-it is demonstrated both in terms
of the effective potential of the string motion and the basin boundary method
reflecting its chaotic character, that a potential barrier exists along the
static radius behind which no trapped oscillations may exist. The trapped
states of the string loops, governed by the interplay of the gravitating mass M
and the cosmic repulsion, are allowed only in Schwarzschild-de Sitter
spacetimes with the cosmological parameter {\lambda}<{\lambda}_trap 0.00497.
The trapped oscillations can extend close to the radius of photon circular
orbit, down to r_mt 3.3M.
| [
{
"created": "Mon, 21 Mar 2011 13:35:20 GMT",
"version": "v1"
}
] | 2011-03-23 | [
[
"Kološ",
"Martin",
""
],
[
"Stuchlík",
"Zdeněk",
""
]
] | Current-carrying string loop dynamics in Schwarzschild-de Sitter spacetimes characterized by the cosmological parameter {\lambda}=1/3{\Lambda}M^2 is investigated. With attention concentrated to the axisymmetric motion of string loops it is shown that the resulting motion is governed by the presence of an outer tension barrier and an inner angular momentum barrier that are influenced by the black hole gravitational field given by the mass M and the cosmic repulsion given by the cosmological constant {\Lambda}. The gravitational attraction could cause capturing of the string having low energy by the black hole or trapping in its vicinity; with high enough energy, the string can escape (scatter) to infinity. The role of the cosmic repulsion becomes important in vicinity of the so-called static radius where the gravitational attraction is balanced by the cosmic repulsion-it is demonstrated both in terms of the effective potential of the string motion and the basin boundary method reflecting its chaotic character, that a potential barrier exists along the static radius behind which no trapped oscillations may exist. The trapped states of the string loops, governed by the interplay of the gravitating mass M and the cosmic repulsion, are allowed only in Schwarzschild-de Sitter spacetimes with the cosmological parameter {\lambda}<{\lambda}_trap 0.00497. The trapped oscillations can extend close to the radius of photon circular orbit, down to r_mt 3.3M. |
gr-qc/9402017 | Kouji Nakamura | Y.Oshiro, K.Nakamura and A.Tomimatsu | Critical Behavior of Black Hole Formation in a Scalar Wave Collapse | DPNU-94-04 (multicol.sty was added.) | Prog.Theor.Phys.91:1265-1270,1994 | 10.1143/PTP.91.1265 | null | gr-qc | null | We present a self-similar model of spherically symmetric collapse of a
massless scalar field with a parameter $p$. The black hole formation is
explicitly shown to occur only in the strong-field implosion of $p >1$. The
field evolution in the critical limit $ p \rightarrow 1 $ is compared with
numerical results found by Choptuik.
| [
{
"created": "Tue, 8 Feb 1994 11:35:39 GMT",
"version": "v1"
},
{
"created": "Thu, 10 Feb 1994 13:46:28 GMT",
"version": "v2"
},
{
"created": "Mon, 14 Feb 1994 10:29:56 GMT",
"version": "v3"
}
] | 2010-11-19 | [
[
"Oshiro",
"Y.",
""
],
[
"Nakamura",
"K.",
""
],
[
"Tomimatsu",
"A.",
""
]
] | We present a self-similar model of spherically symmetric collapse of a massless scalar field with a parameter $p$. The black hole formation is explicitly shown to occur only in the strong-field implosion of $p >1$. The field evolution in the critical limit $ p \rightarrow 1 $ is compared with numerical results found by Choptuik. |
1406.7059 | Kazunari Eda | Kazunari Eda, Ayaka Shoda, Yousuke Itoh, Masaki Ando | Improving parameter estimation accuracy with torsion-bar antennas | 14 pages, 6 figures | Phys. Rev. D 90, 064039 (2014) | 10.1103/PhysRevD.90.064039 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We propose a new antenna configuration of a torsion-bar antenna (TOBA) and
study its performance. A TOBA is a novel type of an antenna for low-frequency
gravitational waves (GWs) which consists of two bar-shaped orthogonal test
masses. Previously only the rotation of the bars on the horizontal plane had
been considered as output signals. In this paper, we introduce a new antenna
configuration for a TOBA to incorporate two additional outputs by measuring the
rotation of the bars on the vertical planes. Such a triple-output TOBA can be
regarded as a network of three coincident but misaligned interferometric
detectors. We investigate its event detection rate and its parameter accuracies
using Fisher analysis. We find that since the triple-output TOBA can
discriminate two polarization modes of a short-duration GW signal even with a
single antenna thanks to having three independent outputs, it improves the
detection rate and the accuracies of waveform parameters drastically.
| [
{
"created": "Fri, 27 Jun 2014 04:42:10 GMT",
"version": "v1"
}
] | 2014-10-01 | [
[
"Eda",
"Kazunari",
""
],
[
"Shoda",
"Ayaka",
""
],
[
"Itoh",
"Yousuke",
""
],
[
"Ando",
"Masaki",
""
]
] | We propose a new antenna configuration of a torsion-bar antenna (TOBA) and study its performance. A TOBA is a novel type of an antenna for low-frequency gravitational waves (GWs) which consists of two bar-shaped orthogonal test masses. Previously only the rotation of the bars on the horizontal plane had been considered as output signals. In this paper, we introduce a new antenna configuration for a TOBA to incorporate two additional outputs by measuring the rotation of the bars on the vertical planes. Such a triple-output TOBA can be regarded as a network of three coincident but misaligned interferometric detectors. We investigate its event detection rate and its parameter accuracies using Fisher analysis. We find that since the triple-output TOBA can discriminate two polarization modes of a short-duration GW signal even with a single antenna thanks to having three independent outputs, it improves the detection rate and the accuracies of waveform parameters drastically. |
2112.01329 | Parthapratim Pradhan | Parthapratim Pradhan | Energy Formula, Surface geometry and Energy Extraction for Kerr-Sen
Black Hole | Published in GRG | General Relativity and Gravitation (2023) 55:25 | 10.1007/s10714-023-03065-z | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | We evaluate the \emph{surface energy~(${\cal E}_{s}^{\pm}$), rotational
energy~(${\cal E}_{r}^{\pm}$) and electromagnetic energy~(${\cal
E}_{em}^{\pm}$)} for a \emph{Kerr-Sen black hole~(BH)} having the event
horizon~(${\cal H}^{+}$) and the Cauchy horizon~(${\cal H}^{-}$).
Interestingly, we find that the \emph{sum of these three energies is equal to
the mass parameter i.e. ${\cal E}_{s}^{\pm}+{\cal E}_{r}^{\pm}+{\cal
E}_{em}^{\pm}={\cal M}$}. Moreover in terms of the \emph{ scale parameter
~$(\zeta_{\pm})$, the distortion parameter~($\xi_{\pm}$) and a new
parameter~$(\sigma_{\pm})$} which corresponds to the area~(${\cal A}_{\pm}$),
the angular momentum ~$(J)$ and the charge parameter~($Q$), we find that the
\emph{mass parameter in a compact form} ${\cal E}_{s}^{\pm}+{\cal
E}_{r}^{\pm}+{\cal E}_{em}^{\pm}={\cal M} =\frac{\zeta_{\pm} }{2}
\sqrt{\frac{1+2\,\sigma_{\pm}^2}{1-\xi_{\pm}^2}}$ %\begin{eqnarray} %{\cal
E}_{s}^{\pm}+{\cal E}_{r}^{\pm}+{\cal E}_{em}^{\pm}={\cal M} =\frac{\zeta_{\pm}
}{2} %\sqrt{\frac{1+2\,\sigma_{\pm}^2}{1-\xi_{\pm}^2}} \nonumber
%\end{eqnarray} which is valid {through all the horizons} (${\cal H}^{\pm}$).
We also compute the \emph{equatorial circumference and polar circumference}
which is a gross measure of the BH surface deformation. It is shown that when
the spinning rate of the BH increases, the \emph{equatorial circumference
increases} while the \emph{polar circumference decreases}. Furthermore, we
compute the exact expression of \emph{rotational energy that should be
extracted from the BH via the Penrose process}. The maximum value of rotational
energy which is extractable should occur for \emph{extremal Kerr-Sen BH} i.e.
${\cal E}_{r}^{+}%=\left(\frac{\sqrt{2}-1}{2}\right)\sqrt{2{\cal M}^2-Q^2}
=\left(\sqrt{2}-1\right)\sqrt{\frac{J}{2}}$.
| [
{
"created": "Thu, 2 Dec 2021 15:31:15 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Feb 2023 19:44:18 GMT",
"version": "v2"
}
] | 2023-02-15 | [
[
"Pradhan",
"Parthapratim",
""
]
] | We evaluate the \emph{surface energy~(${\cal E}_{s}^{\pm}$), rotational energy~(${\cal E}_{r}^{\pm}$) and electromagnetic energy~(${\cal E}_{em}^{\pm}$)} for a \emph{Kerr-Sen black hole~(BH)} having the event horizon~(${\cal H}^{+}$) and the Cauchy horizon~(${\cal H}^{-}$). Interestingly, we find that the \emph{sum of these three energies is equal to the mass parameter i.e. ${\cal E}_{s}^{\pm}+{\cal E}_{r}^{\pm}+{\cal E}_{em}^{\pm}={\cal M}$}. Moreover in terms of the \emph{ scale parameter ~$(\zeta_{\pm})$, the distortion parameter~($\xi_{\pm}$) and a new parameter~$(\sigma_{\pm})$} which corresponds to the area~(${\cal A}_{\pm}$), the angular momentum ~$(J)$ and the charge parameter~($Q$), we find that the \emph{mass parameter in a compact form} ${\cal E}_{s}^{\pm}+{\cal E}_{r}^{\pm}+{\cal E}_{em}^{\pm}={\cal M} =\frac{\zeta_{\pm} }{2} \sqrt{\frac{1+2\,\sigma_{\pm}^2}{1-\xi_{\pm}^2}}$ %\begin{eqnarray} %{\cal E}_{s}^{\pm}+{\cal E}_{r}^{\pm}+{\cal E}_{em}^{\pm}={\cal M} =\frac{\zeta_{\pm} }{2} %\sqrt{\frac{1+2\,\sigma_{\pm}^2}{1-\xi_{\pm}^2}} \nonumber %\end{eqnarray} which is valid {through all the horizons} (${\cal H}^{\pm}$). We also compute the \emph{equatorial circumference and polar circumference} which is a gross measure of the BH surface deformation. It is shown that when the spinning rate of the BH increases, the \emph{equatorial circumference increases} while the \emph{polar circumference decreases}. Furthermore, we compute the exact expression of \emph{rotational energy that should be extracted from the BH via the Penrose process}. The maximum value of rotational energy which is extractable should occur for \emph{extremal Kerr-Sen BH} i.e. ${\cal E}_{r}^{+}%=\left(\frac{\sqrt{2}-1}{2}\right)\sqrt{2{\cal M}^2-Q^2} =\left(\sqrt{2}-1\right)\sqrt{\frac{J}{2}}$. |
gr-qc/0409070 | Hamid Reza Sepangi | S. Jalalzadeh, B. Vakili and H. R. Sepangi | On extra forces from large extra dimensions | 9 pages, no figuers | Phys.Scripta76:122-126,2007 | 10.1088/0031-8949/76/2/002 | null | gr-qc hep-th | null | The motion of a classical test particle moving on a 4-dimensional brane
embedded in an $n$-dimensional bulk is studied in which the brane is allowed to
fluctuate along the extra dimensions. It is shown that these fluctuations
produce three different forces acting on the particle, all stemming from the
effects of extra dimensions. Interpretations are then offered to describe the
origin of these forces and a relationship between the 4 and $n$-dimensional
mass of the particle is obtained by introducing charges associated with large
extra dimensions.
| [
{
"created": "Sun, 19 Sep 2004 08:30:00 GMT",
"version": "v1"
},
{
"created": "Tue, 2 Nov 2004 09:29:19 GMT",
"version": "v2"
},
{
"created": "Sun, 1 Jul 2007 06:17:53 GMT",
"version": "v3"
}
] | 2008-11-26 | [
[
"Jalalzadeh",
"S.",
""
],
[
"Vakili",
"B.",
""
],
[
"Sepangi",
"H. R.",
""
]
] | The motion of a classical test particle moving on a 4-dimensional brane embedded in an $n$-dimensional bulk is studied in which the brane is allowed to fluctuate along the extra dimensions. It is shown that these fluctuations produce three different forces acting on the particle, all stemming from the effects of extra dimensions. Interpretations are then offered to describe the origin of these forces and a relationship between the 4 and $n$-dimensional mass of the particle is obtained by introducing charges associated with large extra dimensions. |
1902.02222 | Diego Rubiera-Garcia | Francisco Cabral, Francisco S. N. Lobo, Diego Rubiera-Garcia | Einstein-Cartan-Dirac gravity with $U(1)$ symmetry breaking | 15 double column pages; v2: removed one section and added content to
other sections. Version accepted for publication on EPJC | Eur. Phys. J. C (2019) 79: 1023 | 10.1140/epjc/s10052-019-7536-3 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Einstein-Cartan theory is an extension of the standard formulation of General
Relativity where torsion (the antisymmetric part of the affine connection) is
non-vanishing. Just as the space-time metric is sourced by the stress-energy
tensor of the matter fields, torsion is sourced via the spin density tensor,
whose physical effects become relevant at very high spin densities. In this
work we introduce an extension of the Einstein-Cartan-Dirac theory with an
electromagnetic (Maxwell) contribution minimally coupled to torsion. This
contribution breaks the $U(1)$ gauge symmetry, which is suggested by the
possibility of a torsion-induced phase transition in the early Universe,
yielding new physics in extreme (spin) density regimes. We obtain the
generalized gravitational, electromagnetic and fermionic field equations for
this theory, estimate the strength of the corrections, and discuss the
corresponding phenomenology. In particular, we briefly address some
astrophysical considerations regarding the relevance of the effects which might
take place inside ultra-dense neutron stars with strong magnetic fields
(magnetars).
| [
{
"created": "Wed, 6 Feb 2019 15:05:33 GMT",
"version": "v1"
},
{
"created": "Sat, 21 Dec 2019 17:10:45 GMT",
"version": "v2"
}
] | 2019-12-30 | [
[
"Cabral",
"Francisco",
""
],
[
"Lobo",
"Francisco S. N.",
""
],
[
"Rubiera-Garcia",
"Diego",
""
]
] | Einstein-Cartan theory is an extension of the standard formulation of General Relativity where torsion (the antisymmetric part of the affine connection) is non-vanishing. Just as the space-time metric is sourced by the stress-energy tensor of the matter fields, torsion is sourced via the spin density tensor, whose physical effects become relevant at very high spin densities. In this work we introduce an extension of the Einstein-Cartan-Dirac theory with an electromagnetic (Maxwell) contribution minimally coupled to torsion. This contribution breaks the $U(1)$ gauge symmetry, which is suggested by the possibility of a torsion-induced phase transition in the early Universe, yielding new physics in extreme (spin) density regimes. We obtain the generalized gravitational, electromagnetic and fermionic field equations for this theory, estimate the strength of the corrections, and discuss the corresponding phenomenology. In particular, we briefly address some astrophysical considerations regarding the relevance of the effects which might take place inside ultra-dense neutron stars with strong magnetic fields (magnetars). |
gr-qc/0208025 | Nese Ozdemir | A.N. Aliev (Feza Gursey Institute), N. Ozdemir (ITU&FGI) | Motion of charged particles around a rotating black hole in a magnetic
field | 25 pages, 2 figures | Mon.Not.Roy.Astron.Soc.336:241-248,2002 | 10.1046/j.1365-8711.2002.05727.x | null | gr-qc astro-ph | null | We study the effects of an external magnetic field, which is assumed to be
uniform at infinity, on the marginally stable circular motion of charged
particles in the equatorial plane of a rotating black hole. We show that the
magnetic field has its greatest effect in enlarging the region of stability
towards the event horizon of the black hole. Using the Hamilton-Jacobi
formalism we obtain the basic equations governing the marginal stability of the
circular orbits and their associated energies and angular momenta. As
instructive examples, we review the case of the marginal stability of the
circular orbits in the Kerr metric, as well as around a Schwarzschild black
hole in a magnetic field. For large enough values of the magnetic field around
a maximally rotating black hole we find the limiting analytical solutions to
the equations governing the radii of marginal stability. We also show that the
presence of a strong magnetic field provides the possibility of relativistic
motions in both direct and retrograde innermost stable circular orbits around a
Kerr black hole.
| [
{
"created": "Fri, 9 Aug 2002 10:46:10 GMT",
"version": "v1"
}
] | 2011-05-23 | [
[
"Aliev",
"A. N.",
"",
"Feza Gursey Institute"
],
[
"Ozdemir",
"N.",
"",
"ITU&FGI"
]
] | We study the effects of an external magnetic field, which is assumed to be uniform at infinity, on the marginally stable circular motion of charged particles in the equatorial plane of a rotating black hole. We show that the magnetic field has its greatest effect in enlarging the region of stability towards the event horizon of the black hole. Using the Hamilton-Jacobi formalism we obtain the basic equations governing the marginal stability of the circular orbits and their associated energies and angular momenta. As instructive examples, we review the case of the marginal stability of the circular orbits in the Kerr metric, as well as around a Schwarzschild black hole in a magnetic field. For large enough values of the magnetic field around a maximally rotating black hole we find the limiting analytical solutions to the equations governing the radii of marginal stability. We also show that the presence of a strong magnetic field provides the possibility of relativistic motions in both direct and retrograde innermost stable circular orbits around a Kerr black hole. |
gr-qc/0108053 | Julio Cesar Fabris | A.B. Batista, J.C. Fabris, S.V.B. Goncalves and Joel Tossa
(Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil) | Quantum cosmological perfect fluid model and its classical analogue | Latex file, 13 pages | Phys.Rev. D65 (2002) 063519 | 10.1103/PhysRevD.65.063519 | null | gr-qc | null | The quantization of gravity coupled to a perfect fluid model leads to a
Schr\"odinger-like equation, where the matter variable plays the role of time.
The wave function can be determined, in the flat case, for an arbitrary
barotropic equation of state $p = \alpha\rho$; solutions can also be found for
the radiative non-flat case. The wave packets are constructed, from which the
expectation value for the scale factor is determined. The quantum scenarios
reveal a bouncing Universe, free from singularity. We show that such quantum
cosmological perfect fluid models admit a universal classical analogue,
represented by the addition, to the ordinary classical model, of a repulsive
stiff matter fluid. The meaning of the existence of this universal classical
analogue is discussed. The quantum cosmological perfect fluid model is, for a
flat spatial section, formally equivalent to a free particle in ordinary
quantum mechanics, for any value of $\alpha$, while the radiative non-flat case
is equivalent to the harmonic oscillator. The repulsive fluid needed to
reproduce the quantum results is the same in both cases.
| [
{
"created": "Wed, 22 Aug 2001 19:01:14 GMT",
"version": "v1"
}
] | 2009-11-07 | [
[
"Batista",
"A. B.",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
],
[
"Fabris",
"J. C.",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
],
[
"Goncalves",
"S. V. B.",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
],
[
"Tossa",
"Joel",
"",
"Departamento de Fisica, Universidade Federal do Espirito Santo, Brazil"
]
] | The quantization of gravity coupled to a perfect fluid model leads to a Schr\"odinger-like equation, where the matter variable plays the role of time. The wave function can be determined, in the flat case, for an arbitrary barotropic equation of state $p = \alpha\rho$; solutions can also be found for the radiative non-flat case. The wave packets are constructed, from which the expectation value for the scale factor is determined. The quantum scenarios reveal a bouncing Universe, free from singularity. We show that such quantum cosmological perfect fluid models admit a universal classical analogue, represented by the addition, to the ordinary classical model, of a repulsive stiff matter fluid. The meaning of the existence of this universal classical analogue is discussed. The quantum cosmological perfect fluid model is, for a flat spatial section, formally equivalent to a free particle in ordinary quantum mechanics, for any value of $\alpha$, while the radiative non-flat case is equivalent to the harmonic oscillator. The repulsive fluid needed to reproduce the quantum results is the same in both cases. |
2206.02551 | Juan Calderon Bustillo | Juan Calderon Bustillo, Nicolas Sanchis-Gual, Samson H.W. Leong,
Koustav Chandra, Alejandro Torres-Forne, Jose A. Font, Carlos Herdeiro, Eugen
Radu, Isaac C.F. Wong and T.G.F. Li | Searching for vector boson-star mergers within LIGO-Virgo
intermediate-mass black-hole merger candidates | Version accepted in Phys.Rev.D. 27 pages, 16 Figures, 4 Appendixes | null | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present the first systematic search for exotic compact mergers in Advanced
LIGO and Virgo events. We compare the short gravitational-wave signals
GW190521, GW190426$\_$190642, GW200220$\_$061928 and the trigger
200114$\_$020818 (or S200114f) to a new catalogue of 759 numerical simulations
of head-on mergers of horizonless exotic compact objects known as Proca stars,
interpreted as self-gravitating lumps of (fuzzy) dark matter sourced by an
ultralight (vector) bosonic particle. The Proca-star merger hypothesis is
strongly rejected with respect to the black hole merger one by GW190426, weakly
rejected by GW200220 and weakly favoured by GW190521 and S200114f. GW190521 and
GW200220 yield highly consistent boson masses of $\mu_{\rm B} =
8.69^{+0.61}_{-0.75}\times10^{-13}$ eV and $\mu_{\rm B} =
9.13^{+1.18}_{-1.30}\times10^{-13}$ eV at the $90\%$ credible level. We conduct
a preliminary population study of the compact binaries behind these events.
Excluding (including) S200114f as a real event, and ignoring boson-mass
consistencies across events, we estimate a fraction of Proca-star mergers of
$\zeta = 0.27^{+0.43}_{-0.25} \ (0.39^{+0.38}_{-0.33})$. We discuss the impact
of boson-mass consistency across events in such estimates. Our results maintain
GW190521 as a Proca-star merger candidate and pave the way towards population
studies considering exotic compact objects.
| [
{
"created": "Mon, 6 Jun 2022 12:24:54 GMT",
"version": "v1"
},
{
"created": "Tue, 14 Jun 2022 14:29:45 GMT",
"version": "v2"
},
{
"created": "Mon, 16 Oct 2023 15:23:54 GMT",
"version": "v3"
}
] | 2023-10-17 | [
[
"Bustillo",
"Juan Calderon",
""
],
[
"Sanchis-Gual",
"Nicolas",
""
],
[
"Leong",
"Samson H. W.",
""
],
[
"Chandra",
"Koustav",
""
],
[
"Torres-Forne",
"Alejandro",
""
],
[
"Font",
"Jose A.",
""
],
[
"Herdeiro",
"Carlos",
""
],
[
"Radu",
"Eugen",
""
],
[
"Wong",
"Isaac C. F.",
""
],
[
"Li",
"T. G. F.",
""
]
] | We present the first systematic search for exotic compact mergers in Advanced LIGO and Virgo events. We compare the short gravitational-wave signals GW190521, GW190426$\_$190642, GW200220$\_$061928 and the trigger 200114$\_$020818 (or S200114f) to a new catalogue of 759 numerical simulations of head-on mergers of horizonless exotic compact objects known as Proca stars, interpreted as self-gravitating lumps of (fuzzy) dark matter sourced by an ultralight (vector) bosonic particle. The Proca-star merger hypothesis is strongly rejected with respect to the black hole merger one by GW190426, weakly rejected by GW200220 and weakly favoured by GW190521 and S200114f. GW190521 and GW200220 yield highly consistent boson masses of $\mu_{\rm B} = 8.69^{+0.61}_{-0.75}\times10^{-13}$ eV and $\mu_{\rm B} = 9.13^{+1.18}_{-1.30}\times10^{-13}$ eV at the $90\%$ credible level. We conduct a preliminary population study of the compact binaries behind these events. Excluding (including) S200114f as a real event, and ignoring boson-mass consistencies across events, we estimate a fraction of Proca-star mergers of $\zeta = 0.27^{+0.43}_{-0.25} \ (0.39^{+0.38}_{-0.33})$. We discuss the impact of boson-mass consistency across events in such estimates. Our results maintain GW190521 as a Proca-star merger candidate and pave the way towards population studies considering exotic compact objects. |
gr-qc/9705079 | Robert Bartnik | Robert Bartnik | Shear-free Null Quasi-Spherical Spacetimes | 20 pages, revtex | J.Math.Phys. 38 (1997) 5774-5791 | 10.1063/1.532165 | UNE-MSCS-96-128 | gr-qc | null | The residual gauge freedom within the null quasi-spherical coordinate
condition is studied, for spacetimes admitting an expanding, shear-free null
foliation. The freedom consists of a boost and rotation at each coordinate
sphere, corresponding to a specification of inertial frame at each sphere.
Explicit formulae involving arbitrary functions of two variables are obtained
for the accelerated Minkowski, Schwarzschild, and Robinson-Trautman spacetimes.
These examples will be useful as test metrics in numerical relativity.
| [
{
"created": "Wed, 28 May 1997 23:40:18 GMT",
"version": "v1"
}
] | 2009-10-30 | [
[
"Bartnik",
"Robert",
""
]
] | The residual gauge freedom within the null quasi-spherical coordinate condition is studied, for spacetimes admitting an expanding, shear-free null foliation. The freedom consists of a boost and rotation at each coordinate sphere, corresponding to a specification of inertial frame at each sphere. Explicit formulae involving arbitrary functions of two variables are obtained for the accelerated Minkowski, Schwarzschild, and Robinson-Trautman spacetimes. These examples will be useful as test metrics in numerical relativity. |
0809.3533 | Manuel Tiglio | David Brown, Peter Diener, Olivier Sarbach, Erik Schnetter, Manuel
Tiglio | Turduckening black holes: an analytical and computational study | Minor changes to match the final version to appear in PRD | Phys.Rev.D79:044023,2009 | 10.1103/PhysRevD.79.044023 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We provide a detailed analysis of several aspects of the turduckening
technique for evolving black holes. At the analytical level we study the
constraint propagation for a general family of BSSN-type formulation of
Einstein's field equations and identify under what conditions the turducken
procedure is rigorously justified and under what conditions constraint
violations will propagate to the outside of the black holes. We present
high-resolution spherically symmetric studies which verify our analytical
predictions. Then we present three dimensional simulations of single distorted
black holes using different variations of the turduckening method and also the
puncture method. We study the effect that these different methods have on the
coordinate conditions, constraint violations, and extracted gravitational
waves. We find that the waves agree up to small but non-vanishing differences,
caused by escaping superluminal gauge modes. These differences become smaller
with increasing detector location.
| [
{
"created": "Sat, 20 Sep 2008 21:48:03 GMT",
"version": "v1"
},
{
"created": "Wed, 21 Jan 2009 15:11:44 GMT",
"version": "v2"
}
] | 2010-05-07 | [
[
"Brown",
"David",
""
],
[
"Diener",
"Peter",
""
],
[
"Sarbach",
"Olivier",
""
],
[
"Schnetter",
"Erik",
""
],
[
"Tiglio",
"Manuel",
""
]
] | We provide a detailed analysis of several aspects of the turduckening technique for evolving black holes. At the analytical level we study the constraint propagation for a general family of BSSN-type formulation of Einstein's field equations and identify under what conditions the turducken procedure is rigorously justified and under what conditions constraint violations will propagate to the outside of the black holes. We present high-resolution spherically symmetric studies which verify our analytical predictions. Then we present three dimensional simulations of single distorted black holes using different variations of the turduckening method and also the puncture method. We study the effect that these different methods have on the coordinate conditions, constraint violations, and extracted gravitational waves. We find that the waves agree up to small but non-vanishing differences, caused by escaping superluminal gauge modes. These differences become smaller with increasing detector location. |
1703.07874 | William Almonacid-Guerrero | William Almonacid and Leonardo Casta\~neda | Generalized Papapetrou's equations of motion for an extended test body
within static and isotropic metrics | 14 pages | null | null | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | Applying Dixon's general equations of motion for extended bodies, we compute
the Papapetrou's equations for an extended test body on static and isotropic
metrics. We incorporate the force and the torque terms which involve multipole
moments, beyond dipole moment, from the energy-momentum tensor. We obtain the
vector form equations for both Corinaldesi-Papapetrou and Tulczyjew-Dixon spin
supplementary conditions. An expanded effective mass, including interactions
between the structure of the body and the gravitational field, is also found.
| [
{
"created": "Wed, 22 Mar 2017 22:42:50 GMT",
"version": "v1"
}
] | 2017-03-24 | [
[
"Almonacid",
"William",
""
],
[
"Castañeda",
"Leonardo",
""
]
] | Applying Dixon's general equations of motion for extended bodies, we compute the Papapetrou's equations for an extended test body on static and isotropic metrics. We incorporate the force and the torque terms which involve multipole moments, beyond dipole moment, from the energy-momentum tensor. We obtain the vector form equations for both Corinaldesi-Papapetrou and Tulczyjew-Dixon spin supplementary conditions. An expanded effective mass, including interactions between the structure of the body and the gravitational field, is also found. |
2408.04603 | Kai Hendriks | Kai Hendriks and Lorenz Zwick and Johan Samsing | Eccentric features in the gravitational wave phase of dynamically formed
black hole binaries | null | null | null | null | gr-qc astro-ph.HE | http://creativecommons.org/licenses/by/4.0/ | We study the gravitational wave (GW) phase shift arising from R{\o}mer delay
in binary black hole (BBH) mergers formed dynamically in three-body systems,
where both the inner orbit of the merging binary and the outer orbit are
eccentric. We provide a semi-analytical model and several analytical
approximations that allow for fast evaluation of both the temporal evolution
and the maximum value of the phase shift. The highest phase shifts occur when
the binary merges close to the pericentre of the outer orbit, and can in this
case be orders-of-magnitude larger compared to the circular limit. At high
outer orbit eccentricities, the orbital curvature leaves distinct imprints onto
the phase shift if the binary passes the outer pericentre during its inspiral.
By comparing with phase-shifts measured in numerical chaotic 3-body
scatterings, we show that our model accurately describes the observed phase of
dynamically assembled binary systems in realistic astrophysical scenarios,
providing a way to directly determine their formation channel via single GW
observations.
| [
{
"created": "Thu, 8 Aug 2024 17:21:58 GMT",
"version": "v1"
}
] | 2024-08-09 | [
[
"Hendriks",
"Kai",
""
],
[
"Zwick",
"Lorenz",
""
],
[
"Samsing",
"Johan",
""
]
] | We study the gravitational wave (GW) phase shift arising from R{\o}mer delay in binary black hole (BBH) mergers formed dynamically in three-body systems, where both the inner orbit of the merging binary and the outer orbit are eccentric. We provide a semi-analytical model and several analytical approximations that allow for fast evaluation of both the temporal evolution and the maximum value of the phase shift. The highest phase shifts occur when the binary merges close to the pericentre of the outer orbit, and can in this case be orders-of-magnitude larger compared to the circular limit. At high outer orbit eccentricities, the orbital curvature leaves distinct imprints onto the phase shift if the binary passes the outer pericentre during its inspiral. By comparing with phase-shifts measured in numerical chaotic 3-body scatterings, we show that our model accurately describes the observed phase of dynamically assembled binary systems in realistic astrophysical scenarios, providing a way to directly determine their formation channel via single GW observations. |
gr-qc/9410036 | null | Lajos Diosi | Quantum Particle As Seen In Light Scattering | 3pp PlainTeX | null | null | null | gr-qc | null | A possible mathematical model has been proposed for motion of illuminated
quantum particles seen by eyes or similar devices mapping the scattered light.
| [
{
"created": "Wed, 26 Oct 1994 16:24:00 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Diosi",
"Lajos",
""
]
] | A possible mathematical model has been proposed for motion of illuminated quantum particles seen by eyes or similar devices mapping the scattered light. |
2205.05973 | Suman Ghosh | Vivek Sharma and Suman Ghosh | Geodesics in Generalised Ellis-Bronnikov Spacetime Embedded in Warped 5D
Background | 20+5 preprint pages, 11 figures; references added, version accepted
in EPJC | null | 10.1140/epjc/s10052-022-10682-6 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We study the particle trajectories in the recently proposed five dimensional
warped (generalized) Ellis-Bronnikov spacetime (5D-WGEB) (which does not
require exotic matter) as well as it's four dimensional counterpart (4D-GEB) in
detail and conduct a comparative study. Analytical approach provides conditions
which determines three types of trajectories (trapped, returning and crossing)
for both 4D and 5D spacetimes. Notably in 5D geometry existence of trapped
trajectories become highly sensitive to the initial conditions. We have solved
the timelike geodesic equations numerically and presented the trajectories
graphically along with corresponding geodesic potentials. We thus distinguished
the roles of the so-called wormhole parameter and the warping factor regarding
their effects on the trajectories and embedding as such. Interestingly, the
5D-WGEB model shows the localization of massive particles around the location
of the brane for growing warp factor and runaway trajectories for decaying warp
factor.
| [
{
"created": "Thu, 12 May 2022 09:27:51 GMT",
"version": "v1"
},
{
"created": "Fri, 12 Aug 2022 07:43:46 GMT",
"version": "v2"
}
] | 2022-09-07 | [
[
"Sharma",
"Vivek",
""
],
[
"Ghosh",
"Suman",
""
]
] | We study the particle trajectories in the recently proposed five dimensional warped (generalized) Ellis-Bronnikov spacetime (5D-WGEB) (which does not require exotic matter) as well as it's four dimensional counterpart (4D-GEB) in detail and conduct a comparative study. Analytical approach provides conditions which determines three types of trajectories (trapped, returning and crossing) for both 4D and 5D spacetimes. Notably in 5D geometry existence of trapped trajectories become highly sensitive to the initial conditions. We have solved the timelike geodesic equations numerically and presented the trajectories graphically along with corresponding geodesic potentials. We thus distinguished the roles of the so-called wormhole parameter and the warping factor regarding their effects on the trajectories and embedding as such. Interestingly, the 5D-WGEB model shows the localization of massive particles around the location of the brane for growing warp factor and runaway trajectories for decaying warp factor. |
0806.3568 | Saibal Ray | Saibal Ray, A A Usmani, F Rahaman, M Kalam and K Chakraborty | Electromagnetic mass model admitting conformal motion | 15 Latex pages with 2 figures | Indian J.Phys.82:1191, 2008 | null | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study charged fluid spheres under the 4-dimensional Einstein-Maxwell
space-time. The solutions thus obtained admitting conformal motion. We also
investigate whether the solutions set provide electromagnetic mass models such
that the physical parameters including the gravitational mass arise from the
electromagnetic field alone. In this connection three cases are studied here in
detail with the propositions: (1) $p = - \rho$, (2) $\sigma e^{\lambda/2} =
\sigma_0$ and (3) $8 \pi p - E^2 = p_0$ where $\rho$, $p$, $\sigma$ are
respectively the usual matter density, fluid pressure and charge density of the
spherical distribution. Based on these assumptions several features are
explored which seems physically very interesting.
| [
{
"created": "Sun, 22 Jun 2008 13:42:56 GMT",
"version": "v1"
}
] | 2011-07-04 | [
[
"Ray",
"Saibal",
""
],
[
"Usmani",
"A A",
""
],
[
"Rahaman",
"F",
""
],
[
"Kalam",
"M",
""
],
[
"Chakraborty",
"K",
""
]
] | We study charged fluid spheres under the 4-dimensional Einstein-Maxwell space-time. The solutions thus obtained admitting conformal motion. We also investigate whether the solutions set provide electromagnetic mass models such that the physical parameters including the gravitational mass arise from the electromagnetic field alone. In this connection three cases are studied here in detail with the propositions: (1) $p = - \rho$, (2) $\sigma e^{\lambda/2} = \sigma_0$ and (3) $8 \pi p - E^2 = p_0$ where $\rho$, $p$, $\sigma$ are respectively the usual matter density, fluid pressure and charge density of the spherical distribution. Based on these assumptions several features are explored which seems physically very interesting. |
1207.3088 | Patricia Schmidt | Patricia Schmidt, Mark Hannam and Sascha Husa | Towards models of gravitational waveforms from generic binaries: A
simple approximate mapping between precessing and non-precessing inspiral
signals | 16 pages, 11 figures, 2 tables; replaced to match published version;
journal ref. added | Phys.Rev. D86 (2012) 104063 | 10.1103/PhysRevD.86.104063 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | One of the greatest theoretical challenges in the build-up to the era of
second-generation gravitational-wave detectors is the modeling of generic
binary waveforms. We introduce an approximation that has the potential to
significantly simplify this problem. We show that generic precessing-binary
inspiral waveforms (covering a seven-dimensional space of intrinsic parameters)
can be mapped to a two-dimensional space of non-precessing binaries,
characterized by the mass ratio and a single effective total spin. The mapping
consists of a time-dependent rotation of the waveforms into the
quadrupole-aligned frame, and is extremely accurate (matches $> 0.99$ with
parameter biases in the total spin of $\Delta \chi \leq 0.04$), even in the
case of transitional precession. In addition, we demonstrate a simple method to
construct hybrid post-Newtonian--numerical-relativity precessing-binary
waveforms in the quadrupole-aligned frame, and provide evidence that our
approximate mapping can be used all the way to the merger. Finally, based on
these results, we outline a general proposal for the construction of generic
waveform models, which will be the focus of future work.
| [
{
"created": "Thu, 12 Jul 2012 20:01:04 GMT",
"version": "v1"
},
{
"created": "Thu, 26 Jul 2012 15:49:30 GMT",
"version": "v2"
},
{
"created": "Mon, 11 Mar 2013 13:30:16 GMT",
"version": "v3"
}
] | 2013-03-12 | [
[
"Schmidt",
"Patricia",
""
],
[
"Hannam",
"Mark",
""
],
[
"Husa",
"Sascha",
""
]
] | One of the greatest theoretical challenges in the build-up to the era of second-generation gravitational-wave detectors is the modeling of generic binary waveforms. We introduce an approximation that has the potential to significantly simplify this problem. We show that generic precessing-binary inspiral waveforms (covering a seven-dimensional space of intrinsic parameters) can be mapped to a two-dimensional space of non-precessing binaries, characterized by the mass ratio and a single effective total spin. The mapping consists of a time-dependent rotation of the waveforms into the quadrupole-aligned frame, and is extremely accurate (matches $> 0.99$ with parameter biases in the total spin of $\Delta \chi \leq 0.04$), even in the case of transitional precession. In addition, we demonstrate a simple method to construct hybrid post-Newtonian--numerical-relativity precessing-binary waveforms in the quadrupole-aligned frame, and provide evidence that our approximate mapping can be used all the way to the merger. Finally, based on these results, we outline a general proposal for the construction of generic waveform models, which will be the focus of future work. |
2005.12053 | Valerio Faraoni | Valerio Faraoni | Cosmic analogues of classic variational problems | 30 pages, 3 figures. Invited paper to appear in Universe | null | null | null | gr-qc physics.class-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Several classic one-dimensional problems of variational calculus originating
in non-relativistic particle mechanics have solutions that are analogues of
spatially homogeneous and isotropic universes. They are ruled by an equation
which is formally a Friedmann equation for a suitable cosmic fluid. These
problems are revisited and their cosmic analogues are pointed out. Some
correspond to the main solutions of cosmology, while others are analogous to
exotic cosmologies with phantom fluids and finite future singularities.
| [
{
"created": "Mon, 25 May 2020 11:49:39 GMT",
"version": "v1"
}
] | 2020-05-26 | [
[
"Faraoni",
"Valerio",
""
]
] | Several classic one-dimensional problems of variational calculus originating in non-relativistic particle mechanics have solutions that are analogues of spatially homogeneous and isotropic universes. They are ruled by an equation which is formally a Friedmann equation for a suitable cosmic fluid. These problems are revisited and their cosmic analogues are pointed out. Some correspond to the main solutions of cosmology, while others are analogous to exotic cosmologies with phantom fluids and finite future singularities. |
gr-qc/0201072 | Pio J. Arias | Rolando Gaitan (Theoretical Physics Group of Physics Departament of
Carabobo's University, Valencia, Venezuela) | On Consistence of Material Coupling in a GL(3,R) Gauge Formulation of
Gravity | 9 pages, LaTeX, title, and abstract changed. To appear in
Mod.Phys.Lett.A, Vol. 18, No. 25 (2003) pp. 1753-1761 | null | null | null | gr-qc | null | A covariant scheme for material coupling with $GL(N,R)$ gauge formulation of
gravity is studied. We revisit a known idea of a Yang-Mills type construction,
where quadratical power of cosmological constant have to be considered in
consistence with vacuum Einstein's gravity. Then, matter coupling with gravity
is introduced and some constraints on fields and background appear. Finally,
exploring the N=3 case we elucidate that introduction of auxiliary fields
decreases the number of these constraints.
| [
{
"created": "Tue, 22 Jan 2002 06:14:15 GMT",
"version": "v1"
},
{
"created": "Sun, 17 Mar 2002 14:08:28 GMT",
"version": "v2"
},
{
"created": "Thu, 7 Aug 2003 20:52:39 GMT",
"version": "v3"
}
] | 2007-05-23 | [
[
"Gaitan",
"Rolando",
"",
"Theoretical Physics Group of Physics Departament of\n Carabobo's University, Valencia, Venezuela"
]
] | A covariant scheme for material coupling with $GL(N,R)$ gauge formulation of gravity is studied. We revisit a known idea of a Yang-Mills type construction, where quadratical power of cosmological constant have to be considered in consistence with vacuum Einstein's gravity. Then, matter coupling with gravity is introduced and some constraints on fields and background appear. Finally, exploring the N=3 case we elucidate that introduction of auxiliary fields decreases the number of these constraints. |
1501.07305 | Ulrich Jentschura | U. D. Jentschura | Gravitational Correction to Vacuum Polarization | 9 pages; RevTeX; typographical errors corrected and references added | Phys.Rev.A 91 (2015) 022112 | 10.1103/PhysRevA.91.022112 | null | gr-qc quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider the gravitational correction to (electronic) vacuum polarization
in the presence of a gravitational background field. The Dirac propagators for
the virtual fermions are modified to include the leading gravitational
correction (potential term) which corresponds to a coordinate-dependent fermion
mass. The mass term is assumed to be uniform over a length scale commensurate
with the virtual electron-positron pair. The on-mass shell renormalization
condition ensures that the gravitational correction vanishes on the mass shell
of the photon, i.e., the speed of light is unaffected by the quantum field
theoretical loop correction, in full agreement with the equivalence principle.
Nontrivial corrections are obtained for off-shell, virtual photons. We compare
our findings to other works on generalized Lorentz transformations and combined
quantum-electrodynamic gravitational corrections to the speed of light which
have recently appeared in the literature.
| [
{
"created": "Wed, 28 Jan 2015 23:00:37 GMT",
"version": "v1"
},
{
"created": "Tue, 17 Feb 2015 21:39:47 GMT",
"version": "v2"
}
] | 2015-02-19 | [
[
"Jentschura",
"U. D.",
""
]
] | We consider the gravitational correction to (electronic) vacuum polarization in the presence of a gravitational background field. The Dirac propagators for the virtual fermions are modified to include the leading gravitational correction (potential term) which corresponds to a coordinate-dependent fermion mass. The mass term is assumed to be uniform over a length scale commensurate with the virtual electron-positron pair. The on-mass shell renormalization condition ensures that the gravitational correction vanishes on the mass shell of the photon, i.e., the speed of light is unaffected by the quantum field theoretical loop correction, in full agreement with the equivalence principle. Nontrivial corrections are obtained for off-shell, virtual photons. We compare our findings to other works on generalized Lorentz transformations and combined quantum-electrodynamic gravitational corrections to the speed of light which have recently appeared in the literature. |
1707.08133 | Hugo Ferreira | Hugo R. C. Ferreira, Carlos A. R. Herdeiro | Stationary scalar clouds around a BTZ black hole | 7 pages, 2 figures | null | 10.1016/j.physletb.2017.08.017 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We establish the existence of stationary clouds of massive test scalar fields
around BTZ black holes. These clouds are zero-modes of the superradiant
instability and are possible when Robin boundary conditions (RBCs) are
considered at the AdS boundary. These boundary conditions are the most general
ones that ensure the AdS space is an isolated system, and include, as a
particular case, the commonly considered Dirichlet or Neumann-type boundary
conditions (DBCs or NBCs). We obtain an explicit, closed form, resonance
condition, relating the RBCs that allow the existence of normalizable (and
regular on and outside the horizon) clouds to the system's parameters. Such
RBCs never include pure DBCs or NBCs. We illustrate the spatial distribution of
these clouds, their energy and angular momentum density for some cases. Our
results show that BTZ black holes with scalar hair can be constructed, as the
non-linear realization of these clouds.
| [
{
"created": "Tue, 25 Jul 2017 18:03:00 GMT",
"version": "v1"
}
] | 2017-09-13 | [
[
"Ferreira",
"Hugo R. C.",
""
],
[
"Herdeiro",
"Carlos A. R.",
""
]
] | We establish the existence of stationary clouds of massive test scalar fields around BTZ black holes. These clouds are zero-modes of the superradiant instability and are possible when Robin boundary conditions (RBCs) are considered at the AdS boundary. These boundary conditions are the most general ones that ensure the AdS space is an isolated system, and include, as a particular case, the commonly considered Dirichlet or Neumann-type boundary conditions (DBCs or NBCs). We obtain an explicit, closed form, resonance condition, relating the RBCs that allow the existence of normalizable (and regular on and outside the horizon) clouds to the system's parameters. Such RBCs never include pure DBCs or NBCs. We illustrate the spatial distribution of these clouds, their energy and angular momentum density for some cases. Our results show that BTZ black holes with scalar hair can be constructed, as the non-linear realization of these clouds. |
1609.03557 | Stephan Reimers | Stephan Reimers, Shruti Paranjape | Dynamics of test particles in the five-dimensional, charged, rotating
EMCS spacetime | 15 pages. (Added references, corrected typos) | Phys. Rev. D 94, 124003 (2016) | 10.1103/PhysRevD.94.124003 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We derive the complete set of geodesic equations for massive and massless
test particles of a five-dimensional, charged, rotating black hole solution of
the Einstein-Maxwell-Chern-Simons field equations in five-dimensional minimal
gauged supergravity and present their analytical solutions in terms of
Weierstra{\ss}' elliptic functions. We study the polar and radial motion,
depending on the black hole and test particle parameters, and characterize the
test particle motion qualitatively by the means of effective potentials. We use
the analytical solutions in order to visualize the test particle motion by two-
and three-dimensional plots.
| [
{
"created": "Mon, 12 Sep 2016 07:01:29 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Sep 2016 12:33:12 GMT",
"version": "v2"
}
] | 2016-12-07 | [
[
"Reimers",
"Stephan",
""
],
[
"Paranjape",
"Shruti",
""
]
] | We derive the complete set of geodesic equations for massive and massless test particles of a five-dimensional, charged, rotating black hole solution of the Einstein-Maxwell-Chern-Simons field equations in five-dimensional minimal gauged supergravity and present their analytical solutions in terms of Weierstra{\ss}' elliptic functions. We study the polar and radial motion, depending on the black hole and test particle parameters, and characterize the test particle motion qualitatively by the means of effective potentials. We use the analytical solutions in order to visualize the test particle motion by two- and three-dimensional plots. |
1109.1481 | Prabir Rudra | Prabir Rudra, Ujjal Debnath, Ritabrata Biswas | Dynamics of Modified Chaplygin Gas in Brane World Scenario: Phase Plane
Analysis | 14 pages, 14 figures | Astrophysics and Space Science (2011) | 10.1007/s10509-011-0967-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this work we investigate the background dynamics when dark energy is
coupled to dark matter with a suitable interaction in the universe described by
brane cosmology. Here DGP and the RSII brane models have been considered
separately. Dark energy in the form of modified Chaplygin gas is considered. A
suitable interaction between dark energy and dark matter is considered in order
to at least alleviate (if not solve) the cosmic coincidence problem. The
dynamical system of equations is solved numerically and a stable scaling
solution is obtained. A significant attempt towards the solution of the cosmic
coincidence problem is taken. The statefinder parameters are also calculated to
classify the dark energy models. Graphs and phase diagrams are drawn to study
the variations of these parameters. It is also seen that the background
dynamics of modified Chaplygin gas is completely consistent with the notion of
an accelerated expansion in the late universe. Finally, it has been shown that
the universe in both the models follows the power law form of expansion around
the critical point, which is consistent with the known results.
| [
{
"created": "Wed, 7 Sep 2011 15:05:42 GMT",
"version": "v1"
},
{
"created": "Wed, 7 Mar 2012 18:24:33 GMT",
"version": "v2"
},
{
"created": "Thu, 8 Mar 2012 20:17:39 GMT",
"version": "v3"
},
{
"created": "Fri, 9 Mar 2012 07:00:21 GMT",
"version": "v4"
}
] | 2012-03-12 | [
[
"Rudra",
"Prabir",
""
],
[
"Debnath",
"Ujjal",
""
],
[
"Biswas",
"Ritabrata",
""
]
] | In this work we investigate the background dynamics when dark energy is coupled to dark matter with a suitable interaction in the universe described by brane cosmology. Here DGP and the RSII brane models have been considered separately. Dark energy in the form of modified Chaplygin gas is considered. A suitable interaction between dark energy and dark matter is considered in order to at least alleviate (if not solve) the cosmic coincidence problem. The dynamical system of equations is solved numerically and a stable scaling solution is obtained. A significant attempt towards the solution of the cosmic coincidence problem is taken. The statefinder parameters are also calculated to classify the dark energy models. Graphs and phase diagrams are drawn to study the variations of these parameters. It is also seen that the background dynamics of modified Chaplygin gas is completely consistent with the notion of an accelerated expansion in the late universe. Finally, it has been shown that the universe in both the models follows the power law form of expansion around the critical point, which is consistent with the known results. |
1301.1417 | Sunil Maharaj | S. D. Maharaj, G. Govender, M. Govender | Radiating stars with generalised Vaidya atmospheres | 10 pages, To appear in Gen. Relativ. Gravit | Gen. Relativ. Gravit. 44: 1089-1099, 2012 | 10.1007/s10714-012-1329-4 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We model the gravitational behaviour of a radiating star when the exterior
geometry is the generalised Vaidya spacetime. The interior matter distribution
is shear-free and undergoing radial heat flow. The exterior energy momentum
tensor is a superposition of a null fluid and a string fluid. An analysis of
the junction conditions at the stellar surface shows that the pressure at the
boundary depends on the interior heat flux and the exterior string density. The
results for a relativistic radiating star undergoing nonadiabatic collapse are
obtained as a special case. For a particular model we demonstrate that the
radiating fluid sphere collapses without the appearance of the horizon at the
boundary.
| [
{
"created": "Tue, 8 Jan 2013 05:33:40 GMT",
"version": "v1"
}
] | 2015-06-12 | [
[
"Maharaj",
"S. D.",
""
],
[
"Govender",
"G.",
""
],
[
"Govender",
"M.",
""
]
] | We model the gravitational behaviour of a radiating star when the exterior geometry is the generalised Vaidya spacetime. The interior matter distribution is shear-free and undergoing radial heat flow. The exterior energy momentum tensor is a superposition of a null fluid and a string fluid. An analysis of the junction conditions at the stellar surface shows that the pressure at the boundary depends on the interior heat flux and the exterior string density. The results for a relativistic radiating star undergoing nonadiabatic collapse are obtained as a special case. For a particular model we demonstrate that the radiating fluid sphere collapses without the appearance of the horizon at the boundary. |
1110.5694 | Kyle Tate | Kyle Tate (Victoria University of Wellington) and Matt Visser
(Victoria University of Wellington) | Realizability of the Lorentzian (n,1)-Simplex | V1: 15 pages, 2 figures. V2: Minor clarifications added to
Introduction and Discussion sections. 1 reference updated. This version
accepted for publication in JHEP. V3: minor updates and clarifications, this
version closely corresponds to the version published in JHEP | JHEP 1201 (2012) 028 | 10.1007/JHEP01(2012)028 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In a previous article [JHEP 1111 (2011) 072; arXiv:1108.4965] we have
developed a Lorentzian version of the Quantum Regge Calculus in which the
significant differences between simplices in Lorentzian signature and Euclidean
signature are crucial. In this article we extend a central result used in the
previous article, regarding the realizability of Lorentzian triangles, to
arbitrary dimension. This technical step will be crucial for developing the
Lorentzian model in the case of most physical interest: 3+1 dimensions.
We first state (and derive in an appendix) the realizability conditions on
the edge-lengths of a Lorentzian n-simplex in total dimension n=d+1, where d is
the number of space-like dimensions. We then show that in any dimension there
is a certain type of simplex which has all of its time-like edge lengths
completely unconstrained by any sort of triangle inequality. This result is the
d+1 dimensional analogue of the 1+1 dimensional case of the Lorentzian
triangle.
| [
{
"created": "Wed, 26 Oct 2011 02:00:16 GMT",
"version": "v1"
},
{
"created": "Fri, 16 Dec 2011 01:32:23 GMT",
"version": "v2"
},
{
"created": "Thu, 12 Jan 2012 03:46:20 GMT",
"version": "v3"
}
] | 2012-01-13 | [
[
"Tate",
"Kyle",
"",
"Victoria University of Wellington"
],
[
"Visser",
"Matt",
"",
"Victoria University of Wellington"
]
] | In a previous article [JHEP 1111 (2011) 072; arXiv:1108.4965] we have developed a Lorentzian version of the Quantum Regge Calculus in which the significant differences between simplices in Lorentzian signature and Euclidean signature are crucial. In this article we extend a central result used in the previous article, regarding the realizability of Lorentzian triangles, to arbitrary dimension. This technical step will be crucial for developing the Lorentzian model in the case of most physical interest: 3+1 dimensions. We first state (and derive in an appendix) the realizability conditions on the edge-lengths of a Lorentzian n-simplex in total dimension n=d+1, where d is the number of space-like dimensions. We then show that in any dimension there is a certain type of simplex which has all of its time-like edge lengths completely unconstrained by any sort of triangle inequality. This result is the d+1 dimensional analogue of the 1+1 dimensional case of the Lorentzian triangle. |
gr-qc/0507123 | Filimonova Irina V | A.Burinskii | Singular Strings in the Rotating Astrophysical Sources: a New Conjecture
on the QPOs and Jet Phenomena | Plenary talk presented at Workshop on High Energy Physics&Field
Theory (Protvino, Russia, 2004) | Proceedings of the XXVII Workshop on the Fundamental Problems of
High Energy Physics, Protvino, June 23-25, 2004 | null | HEPFT/2004/4 | gr-qc | null | Stringy and disklike sources of the rotating compact astrophysical objects
are considered on the base of the Kerr geometry. It is argued that analyticity
of the Kerr solutions may result the appearance of singular strings, which may
be the source of two important astrophysical effects: the jets and QPOs
phenomena.
| [
{
"created": "Fri, 29 Jul 2005 06:41:25 GMT",
"version": "v1"
}
] | 2007-05-23 | [
[
"Burinskii",
"A.",
""
]
] | Stringy and disklike sources of the rotating compact astrophysical objects are considered on the base of the Kerr geometry. It is argued that analyticity of the Kerr solutions may result the appearance of singular strings, which may be the source of two important astrophysical effects: the jets and QPOs phenomena. |
2305.03736 | Gabriel Abell\'an | Gabriel Abell\'an, Nelson Bol\'ivar and Ivaylo Vasilev | Warp drive solutions in spherical coordinates with anisotropic matter
configurations | 34 pages, 25 figures | null | null | null | gr-qc hep-th | http://creativecommons.org/licenses/by/4.0/ | In this work we study the influence of isotropic and anisotropic fluids on
the spherically symmetric warp metric. We evaluate the energy conditions and
the influence of including a cosmological constant type term. We find that,
considering this term, there is a trade-off between the weak and strong energy
conditions. The obtained solutions are numerical and we solve the system for
both the stationary and the full regime. The influence of imposing the zero
expansion condition has been explored. We find a wide diversity of behaviours
for the solutions. In general there are regions of spacetime where the energy
conditions can be at least partially satisfied. Finally, we calculate the value
of the total mass using the density found in the numerical simulations, finding
examples where it remains positive during the entire evolution of the system.
| [
{
"created": "Thu, 4 May 2023 21:16:26 GMT",
"version": "v1"
}
] | 2023-05-09 | [
[
"Abellán",
"Gabriel",
""
],
[
"Bolívar",
"Nelson",
""
],
[
"Vasilev",
"Ivaylo",
""
]
] | In this work we study the influence of isotropic and anisotropic fluids on the spherically symmetric warp metric. We evaluate the energy conditions and the influence of including a cosmological constant type term. We find that, considering this term, there is a trade-off between the weak and strong energy conditions. The obtained solutions are numerical and we solve the system for both the stationary and the full regime. The influence of imposing the zero expansion condition has been explored. We find a wide diversity of behaviours for the solutions. In general there are regions of spacetime where the energy conditions can be at least partially satisfied. Finally, we calculate the value of the total mass using the density found in the numerical simulations, finding examples where it remains positive during the entire evolution of the system. |
1607.04377 | Farhad Darabi | M. Mousavi and F. Darabi | On the stability of Einstein static universe at background level in
massive bigravity | 14 pages, 8 figures, 5 tables, major revision | Nuclear Physics B, 919, (2017), 523 | 10.1016/j.nuclphysb.2017.04.002 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the static cosmological solutions and their stability at background
level in the framework of massive bigravity theory with
Friedmann-Robertson-Walker (FRW) metrics. By the modification proposed in the
cosmological equations subject to a perfect fluid we obtain new solutions
interpreted as the Einstein static universe. It turns out that the
non-vanishing size of initial scale factor of Einstein static universe depends
on the non-vanishing three-dimensional spatial curvature of FRW metrics and
also the graviton's mass. By dynamical system approach and numerical analysis,
we find that the extracted solutions for closed and open universes can be
stable for some viable ranges of equation of state parameter, viable values of
fraction of two scale factors, and viable values of graviton's mass obeying the
hierarchy $m << M_Pl$ which is more cosmologically motivated.
| [
{
"created": "Fri, 15 Jul 2016 04:24:10 GMT",
"version": "v1"
},
{
"created": "Wed, 20 Jul 2016 08:56:37 GMT",
"version": "v2"
},
{
"created": "Tue, 16 May 2017 07:49:55 GMT",
"version": "v3"
}
] | 2017-05-17 | [
[
"Mousavi",
"M.",
""
],
[
"Darabi",
"F.",
""
]
] | We study the static cosmological solutions and their stability at background level in the framework of massive bigravity theory with Friedmann-Robertson-Walker (FRW) metrics. By the modification proposed in the cosmological equations subject to a perfect fluid we obtain new solutions interpreted as the Einstein static universe. It turns out that the non-vanishing size of initial scale factor of Einstein static universe depends on the non-vanishing three-dimensional spatial curvature of FRW metrics and also the graviton's mass. By dynamical system approach and numerical analysis, we find that the extracted solutions for closed and open universes can be stable for some viable ranges of equation of state parameter, viable values of fraction of two scale factors, and viable values of graviton's mass obeying the hierarchy $m << M_Pl$ which is more cosmologically motivated. |
2404.05691 | Lang Liu | Qing-Guo Huang, Chen Yuan, Zu-Cheng Chen and Lang Liu | GW230529_181500: A Potential Primordial Binary Black Hole Merger in the
Mass Gap | 15 pages, 3 figures; Accepted by JCAP | null | null | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | During the fourth observing run of the LIGO-Virgo-KAGRA detector network, the
LIGO Livingston observatory detected a coalescing compact binary,
GW230529_181500, with component masses of $2.5-4.5\, M_\odot$ and $1.2-2.0\,
M_\odot$ at the $90\%$ credible level. The gravitational-wave data alone is
insufficient to determine whether the components are neutron stars or black
holes. In this paper, we propose that GW230529_181500 originated from the
merger of two primordial black holes (PBHs). We estimate a merger rate of
$5.0^{+47.0}_{-4.9} \mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$ for compact binary
coalescences with properties similar to GW230529_181500. Assuming the source is
a PBH-PBH merger, GW230529-like events lead to approximately
$1.7^{+36.2}_{-1.5} \times 10^{-3}$ of the dark matter in the form of PBHs. The
required abundance of PBHs to explain this event is consistent with existing
upper limits derived from microlensing, cosmic microwave background
observations and the null detection of gravitational wave background by
LIGO-Virgo-KAGRA.
| [
{
"created": "Mon, 8 Apr 2024 17:16:16 GMT",
"version": "v1"
},
{
"created": "Thu, 1 Aug 2024 12:18:15 GMT",
"version": "v2"
}
] | 2024-08-02 | [
[
"Huang",
"Qing-Guo",
""
],
[
"Yuan",
"Chen",
""
],
[
"Chen",
"Zu-Cheng",
""
],
[
"Liu",
"Lang",
""
]
] | During the fourth observing run of the LIGO-Virgo-KAGRA detector network, the LIGO Livingston observatory detected a coalescing compact binary, GW230529_181500, with component masses of $2.5-4.5\, M_\odot$ and $1.2-2.0\, M_\odot$ at the $90\%$ credible level. The gravitational-wave data alone is insufficient to determine whether the components are neutron stars or black holes. In this paper, we propose that GW230529_181500 originated from the merger of two primordial black holes (PBHs). We estimate a merger rate of $5.0^{+47.0}_{-4.9} \mathrm{Gpc}^{-3}\,\mathrm{yr}^{-1}$ for compact binary coalescences with properties similar to GW230529_181500. Assuming the source is a PBH-PBH merger, GW230529-like events lead to approximately $1.7^{+36.2}_{-1.5} \times 10^{-3}$ of the dark matter in the form of PBHs. The required abundance of PBHs to explain this event is consistent with existing upper limits derived from microlensing, cosmic microwave background observations and the null detection of gravitational wave background by LIGO-Virgo-KAGRA. |
1103.0610 | Pawe{\l} O. Mazur | Pawel O. Mazur (University of South Carolina, Columbia) and Pawel J.
Morawiec (University of South Carolina, Columbia) | An Optical Geometry Perspective on the Emerging Conformal Field Theory
Behavior on the Cosmological Event Horizon: Massless Fermions on de Sitter
Space | 18 pages | null | null | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We have investigated the emerging conformal field theory behavior on the
interior interface of the region near the cosmological event horizon on an
example of massless Dirac fermions. Indeed, we have constructed and verified
the emerging de Sitter/CFT correspondence for the near cosmological event
horizon region.
It is in this near horizon region where the infinitely thin shell of matter
with the stiffest equation of state (Zeldovich's matter) is placed in the model
for a thermodynamically stable `would be black hole' which is sometimes called
a gravastar or a dark energy star. We put forward the hypothesis to the effect
that the Zeldovich matter consists of the strongly correlated quanta which are
best described by the emerging conformal field theory in the near `would be
horizon' region of a gravastar/dark energy star.
| [
{
"created": "Thu, 3 Mar 2011 05:40:22 GMT",
"version": "v1"
}
] | 2011-03-04 | [
[
"Mazur",
"Pawel O.",
"",
"University of South Carolina, Columbia"
],
[
"Morawiec",
"Pawel J.",
"",
"University of South Carolina, Columbia"
]
] | We have investigated the emerging conformal field theory behavior on the interior interface of the region near the cosmological event horizon on an example of massless Dirac fermions. Indeed, we have constructed and verified the emerging de Sitter/CFT correspondence for the near cosmological event horizon region. It is in this near horizon region where the infinitely thin shell of matter with the stiffest equation of state (Zeldovich's matter) is placed in the model for a thermodynamically stable `would be black hole' which is sometimes called a gravastar or a dark energy star. We put forward the hypothesis to the effect that the Zeldovich matter consists of the strongly correlated quanta which are best described by the emerging conformal field theory in the near `would be horizon' region of a gravastar/dark energy star. |
2209.15488 | Joel Berg\'e | Pierre Touboul, Gilles M\'etris, Manuel Rodrigues, Joel Berg\'e, Alain
Robert, Quentin Baghi, Yves Andr\'e, Judica\"el Bedouet, Damien Boulanger,
Stefanie Bremer, Patrice Carle, Ratana Chhun, Bruno Christophe, Valerio
Cipolla, Thibault Damour, Pascale Danto, Louis Demange, Hansjoerg Dittus,
Oc\'eane Dhuicque, Pierre Fayet, Bernard Foulon, Pierre-Yves Guidotti, Daniel
Hagedorn, Emilie Hardy, Phuong-Anh Huynh, Patrick Kayser, St\'ephanie Lala,
Claus L\"ammerzahl, Vincent Lebat, Fran\c{c}oise Liorzou, Meike List, Frank
L\"offler, Isabelle Panet, Martin Pernot-Borr\`as, Laurent Perraud, Sandrine
Pires, Benjamin Pouilloux, Pascal Prieur, Alexandre Rebray, Serge Reynaud,
Benny Rievers, Hanns Selig, Laura Serron, Timothy Sumner, Nicolas Tanguy,
Patrizia Torresi, Pieter Visser | Result of the MICROSCOPE Weak Equivalence Principle test | Class. Quantum Grav. 39 204009 | Class. Quantum Grav. 39 204009 (2022) | 10.1088/1361-6382/ac84be | null | gr-qc astro-ph.IM hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The space mission MICROSCOPE dedicated to the test of the Equivalence
Principle (EP) operated from April 25, 2016 until the deactivation of the
satellite on October 16, 2018. In this analysis we compare the free-fall
accelerations ($a_{\rm A}$ and $a_{\rm B}$) of two test masses in terms of the
E\"otv\"os parameter $\eta({\rm{A, B}}) = 2 \frac{a_{\rm A}- a_{\rm B}}{a_{\rm
A}+ a_{\rm B}}$. No EP violation has been detected for two test masses, made
from platinum and titanium alloys, in a sequence of 19 segments lasting from 13
to 198 hours down to the limit of the statistical error which is smaller than
$10^{-14}$ for $ \eta({\rm{Ti, Pt}})$. Accumulating data from all segments
leads to $\eta({\rm{Ti, Pt}}) =[-1.5\pm{}2.3{\rm (stat)}\pm{}1.5{\rm (syst)}]
\times{}10^{-15}$ showing no EP violation at the level of $2.7\times{}10^{-15}$
if we combine stochastic and systematic errors quadratically. This represents
an improvement of almost two orders of magnitude with respect to the previous
best such test performed by the E\"ot-Wash group. The reliability of this limit
has been verified by comparing the free falls of two test masses of the same
composition (platinum) leading to a null E\"otv\"os parameter with a
statistical uncertainty of $1.1\times{}10^{-15}$.
| [
{
"created": "Fri, 30 Sep 2022 14:21:33 GMT",
"version": "v1"
}
] | 2023-04-14 | [
[
"Touboul",
"Pierre",
""
],
[
"Métris",
"Gilles",
""
],
[
"Rodrigues",
"Manuel",
""
],
[
"Bergé",
"Joel",
""
],
[
"Robert",
"Alain",
""
],
[
"Baghi",
"Quentin",
""
],
[
"André",
"Yves",
""
],
[
"Bedouet",
"Judicaël",
""
],
[
"Boulanger",
"Damien",
""
],
[
"Bremer",
"Stefanie",
""
],
[
"Carle",
"Patrice",
""
],
[
"Chhun",
"Ratana",
""
],
[
"Christophe",
"Bruno",
""
],
[
"Cipolla",
"Valerio",
""
],
[
"Damour",
"Thibault",
""
],
[
"Danto",
"Pascale",
""
],
[
"Demange",
"Louis",
""
],
[
"Dittus",
"Hansjoerg",
""
],
[
"Dhuicque",
"Océane",
""
],
[
"Fayet",
"Pierre",
""
],
[
"Foulon",
"Bernard",
""
],
[
"Guidotti",
"Pierre-Yves",
""
],
[
"Hagedorn",
"Daniel",
""
],
[
"Hardy",
"Emilie",
""
],
[
"Huynh",
"Phuong-Anh",
""
],
[
"Kayser",
"Patrick",
""
],
[
"Lala",
"Stéphanie",
""
],
[
"Lämmerzahl",
"Claus",
""
],
[
"Lebat",
"Vincent",
""
],
[
"Liorzou",
"Françoise",
""
],
[
"List",
"Meike",
""
],
[
"Löffler",
"Frank",
""
],
[
"Panet",
"Isabelle",
""
],
[
"Pernot-Borràs",
"Martin",
""
],
[
"Perraud",
"Laurent",
""
],
[
"Pires",
"Sandrine",
""
],
[
"Pouilloux",
"Benjamin",
""
],
[
"Prieur",
"Pascal",
""
],
[
"Rebray",
"Alexandre",
""
],
[
"Reynaud",
"Serge",
""
],
[
"Rievers",
"Benny",
""
],
[
"Selig",
"Hanns",
""
],
[
"Serron",
"Laura",
""
],
[
"Sumner",
"Timothy",
""
],
[
"Tanguy",
"Nicolas",
""
],
[
"Torresi",
"Patrizia",
""
],
[
"Visser",
"Pieter",
""
]
] | The space mission MICROSCOPE dedicated to the test of the Equivalence Principle (EP) operated from April 25, 2016 until the deactivation of the satellite on October 16, 2018. In this analysis we compare the free-fall accelerations ($a_{\rm A}$ and $a_{\rm B}$) of two test masses in terms of the E\"otv\"os parameter $\eta({\rm{A, B}}) = 2 \frac{a_{\rm A}- a_{\rm B}}{a_{\rm A}+ a_{\rm B}}$. No EP violation has been detected for two test masses, made from platinum and titanium alloys, in a sequence of 19 segments lasting from 13 to 198 hours down to the limit of the statistical error which is smaller than $10^{-14}$ for $ \eta({\rm{Ti, Pt}})$. Accumulating data from all segments leads to $\eta({\rm{Ti, Pt}}) =[-1.5\pm{}2.3{\rm (stat)}\pm{}1.5{\rm (syst)}] \times{}10^{-15}$ showing no EP violation at the level of $2.7\times{}10^{-15}$ if we combine stochastic and systematic errors quadratically. This represents an improvement of almost two orders of magnitude with respect to the previous best such test performed by the E\"ot-Wash group. The reliability of this limit has been verified by comparing the free falls of two test masses of the same composition (platinum) leading to a null E\"otv\"os parameter with a statistical uncertainty of $1.1\times{}10^{-15}$. |
gr-qc/9901071 | Adrian P. Gentle | Adrian P. Gentle | Simplicial Brill wave initial data | 17 pages, LaTeX 2e, 13 eps figures. Submitted to CQG | Class.Quant.Grav. 16 (1999) 1987-2003 | 10.1088/0264-9381/16/6/327 | LAUR-99-304 | gr-qc | null | Regge calculus is used to construct initial data for vacuum axisymmetric
Brill waves at a moment of time symmetry. We argue that only a tetrahedral
lattice can successfully reproduce the continuum solution, and develop a
simplicial axisymmetric lattice based on the co-ordinate structure of the
continuum metric. This is used to construct initial data for Brill waves in an
otherwise flat spacetime, and for the distorted black hole spacetime of
Bernstein. These initial data sets are shown to be second order accurate
approximations to the corresponding continuum solutions.
| [
{
"created": "Mon, 25 Jan 1999 18:14:08 GMT",
"version": "v1"
}
] | 2009-10-31 | [
[
"Gentle",
"Adrian P.",
""
]
] | Regge calculus is used to construct initial data for vacuum axisymmetric Brill waves at a moment of time symmetry. We argue that only a tetrahedral lattice can successfully reproduce the continuum solution, and develop a simplicial axisymmetric lattice based on the co-ordinate structure of the continuum metric. This is used to construct initial data for Brill waves in an otherwise flat spacetime, and for the distorted black hole spacetime of Bernstein. These initial data sets are shown to be second order accurate approximations to the corresponding continuum solutions. |
1912.06117 | Charles Dalang | Charles Dalang, Pierre Fleury, Lucas Lombriser | Horndeski gravity and standard sirens | 17 pages, 1 figure. v2: title changed upon PRD request; improved
discussion on scalar waves in Sec. II.D; extended discussion on polarization
in Sec. III.C; detailed comparison with another recent work in Appendix E;
version accepted for publication in PRD | Phys. Rev. D 102, 044036 (2020) | 10.1103/PhysRevD.102.044036 | IFT-UAM/CSIC-168 | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Standard sirens have been proposed as probes of alternative theories of
gravity, such as Horndeski models. Hitherto, all studies have been conducted on
a homogeneous-isotropic cosmological background, which is unable to
consistently account for realistic distributions of matter, and for
inhomogeneities in the Horndeski scalar field. Yet, the latter are essential
for screening mechanisms. In this article, we comprehensively analyze the
propagation of Horndeski gravitational waves in an arbitrary background
spacetime and scalar field. We restrict to the class of theories in which
gravitational waves propagate at light speed, and work in the geometric-optics
regime. We find that kinetic braiding only produces a nonphysical longitudinal
mode, whereas conformal coupling affects the amplitude of the standard
transverse modes but not their polarization. We confirm that any observable
deviation from general relativity depends on the local value of the effective
Planck mass at emission and reception of the wave. This result is interpreted
as the conservation of the number of gravitons.
| [
{
"created": "Thu, 12 Dec 2019 18:31:49 GMT",
"version": "v1"
},
{
"created": "Wed, 2 Sep 2020 15:42:47 GMT",
"version": "v2"
},
{
"created": "Thu, 3 Sep 2020 09:23:46 GMT",
"version": "v3"
}
] | 2020-09-04 | [
[
"Dalang",
"Charles",
""
],
[
"Fleury",
"Pierre",
""
],
[
"Lombriser",
"Lucas",
""
]
] | Standard sirens have been proposed as probes of alternative theories of gravity, such as Horndeski models. Hitherto, all studies have been conducted on a homogeneous-isotropic cosmological background, which is unable to consistently account for realistic distributions of matter, and for inhomogeneities in the Horndeski scalar field. Yet, the latter are essential for screening mechanisms. In this article, we comprehensively analyze the propagation of Horndeski gravitational waves in an arbitrary background spacetime and scalar field. We restrict to the class of theories in which gravitational waves propagate at light speed, and work in the geometric-optics regime. We find that kinetic braiding only produces a nonphysical longitudinal mode, whereas conformal coupling affects the amplitude of the standard transverse modes but not their polarization. We confirm that any observable deviation from general relativity depends on the local value of the effective Planck mass at emission and reception of the wave. This result is interpreted as the conservation of the number of gravitons. |
2303.01976 | Valeriy Obukhov | V. V. Obukhov | Exact solutions of Maxwell equations in homogeneous spaces with the
group of motions $G_3(VIII)$ | Will be publised in Symmetry, 15 pages | null | null | null | gr-qc math-ph math.MP | http://creativecommons.org/licenses/by-nc-nd/4.0/ | The problem of classification of exact solutions of Maxwell's vacuum
equations for admissible electromagnetic fields and homogeneous space-time with
the group of motions $G_3(VIII)$ according to the Bianchi classification is
considered. All non-equivalent solutions are found. The classification problem
for remaining groups of motions $G_3(N)$ has already been solved in the other
papers. That is why all non-equivalent solutions of empty Maxwell equations for
all homogeneous spaces with admissible electromagnetic fields are known now.
| [
{
"created": "Thu, 2 Mar 2023 08:25:50 GMT",
"version": "v1"
}
] | 2023-03-06 | [
[
"Obukhov",
"V. V.",
""
]
] | The problem of classification of exact solutions of Maxwell's vacuum equations for admissible electromagnetic fields and homogeneous space-time with the group of motions $G_3(VIII)$ according to the Bianchi classification is considered. All non-equivalent solutions are found. The classification problem for remaining groups of motions $G_3(N)$ has already been solved in the other papers. That is why all non-equivalent solutions of empty Maxwell equations for all homogeneous spaces with admissible electromagnetic fields are known now. |
1407.3545 | Giampiero Esposito Dr. | Emmanuele Battista, Giampiero Esposito | Full three-body problem in effective-field-theory models of gravity | 23 pages, 1 figure, Revtex4. In the final version, Section VII is
much longer, the misprints have been amended, and new References have been
included | Phys.Rev. D90 (2014) 084010 | 10.1103/PhysRevD.90.084010 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Recent work in the literature has studied the restricted three-body problem
within the framework of effective-field-theory models of gravity. This paper
extends such a program by considering the full three-body problem, when the
Newtonian potential is replaced by a more general central potential which
depends on the mutual separations of the three bodies. The general form of the
equations of motion is written down, and they are studied when the interaction
potential reduces to the quantum-corrected central potential considered
recently in the literature. A recursive algorithm is found for solving the
associated variational equations, which describe small departures from given
periodic solutions of the equations of motion. Our scheme involves repeated
application of a 2 x 2 matrix of first-order linear differential operators.
| [
{
"created": "Mon, 14 Jul 2014 06:36:54 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Sep 2014 17:34:32 GMT",
"version": "v2"
}
] | 2014-10-17 | [
[
"Battista",
"Emmanuele",
""
],
[
"Esposito",
"Giampiero",
""
]
] | Recent work in the literature has studied the restricted three-body problem within the framework of effective-field-theory models of gravity. This paper extends such a program by considering the full three-body problem, when the Newtonian potential is replaced by a more general central potential which depends on the mutual separations of the three bodies. The general form of the equations of motion is written down, and they are studied when the interaction potential reduces to the quantum-corrected central potential considered recently in the literature. A recursive algorithm is found for solving the associated variational equations, which describe small departures from given periodic solutions of the equations of motion. Our scheme involves repeated application of a 2 x 2 matrix of first-order linear differential operators. |
2201.12897 | Alexander Zhidenko | R. A. Konoplya and A. Zhidenko | Quasinormal ringing of general spherically symmetric parametrized black
holes | 10 pages, 9 figures | Phys. Rev. D 105, 104032 (2022) | 10.1103/PhysRevD.105.104032 | null | gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The general parametrization of spherically symmetric and asymptotically flat
black-hole spacetimes in arbitrary metric theories of gravity was suggested in
[3]. The parametrization is based on the continued fraction expansion in terms
of the compact radial coordinate and has superior convergence and strict
hierarchy of parameters. It is known that some observable quantities, related
to particle motion around the black hole, such as the eikonal quasinormal
modes, radius of the shadow, frequency at the innermost stable circular orbit,
and others, depend mostly on only a few of the lowest coefficients of the
parametrization. Here we continue this approach by studying the dominant
(low-lying) quasinormal modes for such generally parametrized black holes. We
show that, due to the hierarchy of parameters, the dominant quasinormal
frequencies are also well determined by only the first few coefficients of the
expansion for the so-called moderate black-hole geometries. The latter are
characterized by a relatively slow change of the metric functions in the
radiation zone near the black hole. The nonmoderate metrics, which change
strongly between the event horizon and the innermost stable circular orbit are
usually characterized by echoes or by the distinctive (from the Einstein case)
quasinormal ringing which does not match the current observational data.
Therefore, the compact description of a black-hole spacetime in terms of the
truncated general parametrization is an effective formalism for testing strong
gravity and imposing constraints on allowed black-hole geometries.
| [
{
"created": "Sun, 30 Jan 2022 19:39:46 GMT",
"version": "v1"
},
{
"created": "Tue, 17 May 2022 10:51:53 GMT",
"version": "v2"
}
] | 2022-05-18 | [
[
"Konoplya",
"R. A.",
""
],
[
"Zhidenko",
"A.",
""
]
] | The general parametrization of spherically symmetric and asymptotically flat black-hole spacetimes in arbitrary metric theories of gravity was suggested in [3]. The parametrization is based on the continued fraction expansion in terms of the compact radial coordinate and has superior convergence and strict hierarchy of parameters. It is known that some observable quantities, related to particle motion around the black hole, such as the eikonal quasinormal modes, radius of the shadow, frequency at the innermost stable circular orbit, and others, depend mostly on only a few of the lowest coefficients of the parametrization. Here we continue this approach by studying the dominant (low-lying) quasinormal modes for such generally parametrized black holes. We show that, due to the hierarchy of parameters, the dominant quasinormal frequencies are also well determined by only the first few coefficients of the expansion for the so-called moderate black-hole geometries. The latter are characterized by a relatively slow change of the metric functions in the radiation zone near the black hole. The nonmoderate metrics, which change strongly between the event horizon and the innermost stable circular orbit are usually characterized by echoes or by the distinctive (from the Einstein case) quasinormal ringing which does not match the current observational data. Therefore, the compact description of a black-hole spacetime in terms of the truncated general parametrization is an effective formalism for testing strong gravity and imposing constraints on allowed black-hole geometries. |
1302.7142 | Etera R. Livine | Etera R. Livine, Johannes Tambornino | Holonomy Operator and Quantization Ambiguities on Spinor Space | 14 pages | Phys. Rev. D 87, 104014 (2013) | 10.1103/PhysRevD.87.104014 | null | gr-qc math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We construct the holonomy-flux operator algebra in the recently developed
spinor formulation of loop gravity. We show that, when restricting to
SU(2)-gauge invariant operators, the familiar grasping and Wilson loop
operators are written as composite operators built from the gauge-invariant
`generalized ladder operators' recently introduced in the U(N) approach to
intertwiners and spin networks. We comment on quantization ambiguities that
appear in the definition of the holonomy operator and use these ambiguities as
a toy model to test a class of quantization ambiguities which is present in the
standard regularization and definition of the Hamiltonian constraint operator
in loop quantum gravity.
| [
{
"created": "Thu, 28 Feb 2013 10:31:06 GMT",
"version": "v1"
},
{
"created": "Mon, 4 Mar 2013 09:35:03 GMT",
"version": "v2"
}
] | 2013-11-08 | [
[
"Livine",
"Etera R.",
""
],
[
"Tambornino",
"Johannes",
""
]
] | We construct the holonomy-flux operator algebra in the recently developed spinor formulation of loop gravity. We show that, when restricting to SU(2)-gauge invariant operators, the familiar grasping and Wilson loop operators are written as composite operators built from the gauge-invariant `generalized ladder operators' recently introduced in the U(N) approach to intertwiners and spin networks. We comment on quantization ambiguities that appear in the definition of the holonomy operator and use these ambiguities as a toy model to test a class of quantization ambiguities which is present in the standard regularization and definition of the Hamiltonian constraint operator in loop quantum gravity. |
2005.11702 | Leandros Perivolaropoulos | G. Alestas, G. V. Kraniotis and L. Perivolaropoulos | Existence and Stability of Static Spherical Fluid Shells in a
Schwarzschild-Rindler-anti-de Sitter Metric | 10 pages, 5 figures. Accepted in Phys. Rev. D (to appear).
Publication version (includes minor modifications). The mathematica files for
the numerical analysis may be downloaded from
https://github.com/GeorgeAlestas/Fluid_Shell_Stability | Phys. Rev. D 102, 104015 (2020) | 10.1103/PhysRevD.102.104015 | null | gr-qc hep-ph hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We demonstrate the existence of static stable spherical fluid shells in the
Schwarzschild-Rindler-anti-de Sitter (SRAdS) spacetime where $ds^2 = f(r)dt^{2}
-\frac{dr^{2}}{f(r)}-r^{2}(d\theta ^2 +\sin ^2 \theta d\phi ^2)$ with $f(r) = 1
-\frac{2Gm}{r} + 2 b r -\frac{\Lambda}{3}r^2$. This is an alternative to the
well known gravastar geometry where the stability emerges due to the
combination of the repulsive forces of the interior de Sitter space with the
attractive forces of the exterior Schwarzschild spacetime. In the SRAdS
spacetime the repulsion that leads to stability of the shell comes from a
negative Rindler term while the Schwarzschild and anti-de Sitter terms are
attractive. We demonstrate the existence of such stable spherical shells for
three shell fluid equations of state: vacuum shell ($p=-\sigma$), stiff matter
shell ($p=\sigma$) and dust shell ($p=0$) where $p$ is the shell pressure and
$\sigma$ is the shell surface density. We also identify the metric parameter
conditions that need to be satisfied for shell stability in each case. The
vacuum stable shell solution in the SRAdS spacetime is consistent with previous
studies by two of the authors that demonstrated the existence sf stable
spherical scalar field domain walls in the SRAdS spacetime.
| [
{
"created": "Sun, 24 May 2020 09:54:01 GMT",
"version": "v1"
},
{
"created": "Mon, 9 Nov 2020 20:43:30 GMT",
"version": "v2"
}
] | 2020-11-11 | [
[
"Alestas",
"G.",
""
],
[
"Kraniotis",
"G. V.",
""
],
[
"Perivolaropoulos",
"L.",
""
]
] | We demonstrate the existence of static stable spherical fluid shells in the Schwarzschild-Rindler-anti-de Sitter (SRAdS) spacetime where $ds^2 = f(r)dt^{2} -\frac{dr^{2}}{f(r)}-r^{2}(d\theta ^2 +\sin ^2 \theta d\phi ^2)$ with $f(r) = 1 -\frac{2Gm}{r} + 2 b r -\frac{\Lambda}{3}r^2$. This is an alternative to the well known gravastar geometry where the stability emerges due to the combination of the repulsive forces of the interior de Sitter space with the attractive forces of the exterior Schwarzschild spacetime. In the SRAdS spacetime the repulsion that leads to stability of the shell comes from a negative Rindler term while the Schwarzschild and anti-de Sitter terms are attractive. We demonstrate the existence of such stable spherical shells for three shell fluid equations of state: vacuum shell ($p=-\sigma$), stiff matter shell ($p=\sigma$) and dust shell ($p=0$) where $p$ is the shell pressure and $\sigma$ is the shell surface density. We also identify the metric parameter conditions that need to be satisfied for shell stability in each case. The vacuum stable shell solution in the SRAdS spacetime is consistent with previous studies by two of the authors that demonstrated the existence sf stable spherical scalar field domain walls in the SRAdS spacetime. |
2209.14961 | Magd Elias Kahil | Magd E. Kahil, Samah A. Ammar and Shymaa A. Refaey | Motion of Spinning and Spinning Deviation Density Tensors in Riemannian
Geometry | 15 LaTeX pages | null | 10.1134/S020228932302007X | null | gr-qc hep-th | http://creativecommons.org/publicdomain/zero/1.0/ | Equations of motion of spinning density for extended objects, and
corresponding deviation equations are derived. The problem of motion for a
variable mass to a spinning extended object is obtained. Spinning fluids may be
considered as a special case to express the motion of spinning density for
extended objects. Meanwhile, spinning density tensor can be expressed in terms
of tetrad formalism of General Relativity to be regarded as a gauge theory of
gravity. Equations of spinning and spinning deviation density tensors have been
derived using a specific type of Bazanski Lagrangian is performed.
| [
{
"created": "Thu, 29 Sep 2022 17:35:07 GMT",
"version": "v1"
},
{
"created": "Wed, 26 Oct 2022 03:53:13 GMT",
"version": "v2"
}
] | 2023-06-28 | [
[
"Kahil",
"Magd E.",
""
],
[
"Ammar",
"Samah A.",
""
],
[
"Refaey",
"Shymaa A.",
""
]
] | Equations of motion of spinning density for extended objects, and corresponding deviation equations are derived. The problem of motion for a variable mass to a spinning extended object is obtained. Spinning fluids may be considered as a special case to express the motion of spinning density for extended objects. Meanwhile, spinning density tensor can be expressed in terms of tetrad formalism of General Relativity to be regarded as a gauge theory of gravity. Equations of spinning and spinning deviation density tensors have been derived using a specific type of Bazanski Lagrangian is performed. |
gr-qc/0505105 | Alberto Diez-Tejedor | Alberto Diez-Tejedor and Alexander Feinstein | Accelerating Universes from Short-Range Interactions | 4 pages, 1 figure. Discussion expanded. Some references added.
Matches version in print. To appear in Phys. Lett. A | Phys.Lett. A350 (2006) 315-318 | 10.1016/j.physleta.2005.10.030 | null | gr-qc astro-ph hep-th | null | We show that short-range interactions between the fundamental particles in
the universe can drive a period of accelerated expansion. This description fits
the early universe. In the present day universe, if one postulates short-range
interactions or a sort of "shielded gravity", the picture may repeat.
| [
{
"created": "Fri, 20 May 2005 08:37:14 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Oct 2005 12:59:43 GMT",
"version": "v2"
}
] | 2009-11-11 | [
[
"Diez-Tejedor",
"Alberto",
""
],
[
"Feinstein",
"Alexander",
""
]
] | We show that short-range interactions between the fundamental particles in the universe can drive a period of accelerated expansion. This description fits the early universe. In the present day universe, if one postulates short-range interactions or a sort of "shielded gravity", the picture may repeat. |
2405.06031 | Mariam Campbell | Mariam Campbell, Richard Daniel, Peter K. S. Dunsby, and Carsten van
de Bruck | Bouncing cosmologies in the presence of a Dirac-Born-Infeld field | 18 pages, 5 figures, 3 tables | Phys. Rev. D 110, 043505 (2024) | 10.1103/PhysRevD.110.043505 | null | gr-qc | http://creativecommons.org/licenses/by/4.0/ | We perform a detailed dynamical system analysis for the behaviour of a
Dirac-Born-Infeld (DBI) field in a spatially closed
Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmology. The DBI field is
characterised by a potential and brane tension. We study power-law or
exponential functions for the potential and tension. We find that in a
spatially closed FLRW cosmology, a DBI field in the ultra-relativistic limit
allows for a broader range of initial conditions resulting in a bouncing
universe than in the non-relativistic limit. We further note that the range of
initial conditions allowing for a bounce is larger if we consider power-law
functions for the potential and tension, compared to the exponential case. Our
dynamical analysis shows that a DBI field does not exhibit stable cyclical
behaviour, including the case in which a negative cosmological constant is
present.
| [
{
"created": "Thu, 9 May 2024 18:02:23 GMT",
"version": "v1"
}
] | 2024-08-06 | [
[
"Campbell",
"Mariam",
""
],
[
"Daniel",
"Richard",
""
],
[
"Dunsby",
"Peter K. S.",
""
],
[
"van de Bruck",
"Carsten",
""
]
] | We perform a detailed dynamical system analysis for the behaviour of a Dirac-Born-Infeld (DBI) field in a spatially closed Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmology. The DBI field is characterised by a potential and brane tension. We study power-law or exponential functions for the potential and tension. We find that in a spatially closed FLRW cosmology, a DBI field in the ultra-relativistic limit allows for a broader range of initial conditions resulting in a bouncing universe than in the non-relativistic limit. We further note that the range of initial conditions allowing for a bounce is larger if we consider power-law functions for the potential and tension, compared to the exponential case. Our dynamical analysis shows that a DBI field does not exhibit stable cyclical behaviour, including the case in which a negative cosmological constant is present. |
1412.6580 | Kenji Tomita | Kenji Tomita | Cosmological perturbations in the (1+3+6)-dimensional space-times | 34 pages, 2 figures | Prog. Theor. Expt. Phys. 2014, 123E01 | 10.1093/Ptep/ptu164 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Cosmological perturbations in the (1+3+6)-dimensional space-times including
photon gas without viscous processes are studied on the basis of Abbott et
al.'s formalism. Space-times consist of the outer space (the 3-dimensional
expanding section) and the inner space (the 6-dimensional section). The inner
space expands initially and contracts later. Abbott et al. derived only
power-type solutions in the small wave-number limit which appear at the final
stage of the space-times. In this paper, we derive not only small wave-number
solutions, but also large wave-number solutions. It is found that the latter
solutions depend on the two wave-numbers k_r and k_R (which are defined in the
outer and inner spaces, respectively), and that the k_r-dependent and
k_R-dependent parts dominate the total perturbations when (k_r/r(t))/(k_R/R(t))
>> 1 or << 1, respectively, where r(t) and R(t) are the scale-factors in the
outer and inner spaces. By comparing the behaviors of these perturbations,
moreover, changes in the spectrum of perturbations in the outer space with time
are discussed.
| [
{
"created": "Sat, 20 Dec 2014 02:06:07 GMT",
"version": "v1"
}
] | 2014-12-23 | [
[
"Tomita",
"Kenji",
""
]
] | Cosmological perturbations in the (1+3+6)-dimensional space-times including photon gas without viscous processes are studied on the basis of Abbott et al.'s formalism. Space-times consist of the outer space (the 3-dimensional expanding section) and the inner space (the 6-dimensional section). The inner space expands initially and contracts later. Abbott et al. derived only power-type solutions in the small wave-number limit which appear at the final stage of the space-times. In this paper, we derive not only small wave-number solutions, but also large wave-number solutions. It is found that the latter solutions depend on the two wave-numbers k_r and k_R (which are defined in the outer and inner spaces, respectively), and that the k_r-dependent and k_R-dependent parts dominate the total perturbations when (k_r/r(t))/(k_R/R(t)) >> 1 or << 1, respectively, where r(t) and R(t) are the scale-factors in the outer and inner spaces. By comparing the behaviors of these perturbations, moreover, changes in the spectrum of perturbations in the outer space with time are discussed. |
2105.10086 | Andrzej G\"orlich | Jan Ambj{\o}rn, Zbigniew Drogosz, Jakub Gizbert-Studnicki, Andrzej
G\"orlich, Jerzy Jurkiewicz, D\'aniel N\'emeth | Scalar fields in Causal Dynamical Triangulations | 51 pages | null | 10.1088/1361-6382/ac2135 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A typical geometry extracted from the path integral of a quantum theory of
gravity might be quite complicated in the UV region. Even if such a
configuration is not physical, it may be of interest to understand the details
of its nature, since some universal features can be important for the physics
of the model. If the formalism describing the geometry is coordinate
independent, such understanding may be facilitated by the use of suitable
coordinate systems. In this article we use scalar fields that solve Laplace's
equation to introduce coordinates on geometries with a toroidal topology. Using
these coordinates we observe what we denote as the "cosmic voids and filaments"
structure, even if no matter is present in the theory. We also show that if the
scalar fields we used as coordinates are dynamically coupled to geometry, they
can change it in a dramatic way.
| [
{
"created": "Fri, 21 May 2021 01:34:44 GMT",
"version": "v1"
}
] | 2021-10-27 | [
[
"Ambjørn",
"Jan",
""
],
[
"Drogosz",
"Zbigniew",
""
],
[
"Gizbert-Studnicki",
"Jakub",
""
],
[
"Görlich",
"Andrzej",
""
],
[
"Jurkiewicz",
"Jerzy",
""
],
[
"Németh",
"Dániel",
""
]
] | A typical geometry extracted from the path integral of a quantum theory of gravity might be quite complicated in the UV region. Even if such a configuration is not physical, it may be of interest to understand the details of its nature, since some universal features can be important for the physics of the model. If the formalism describing the geometry is coordinate independent, such understanding may be facilitated by the use of suitable coordinate systems. In this article we use scalar fields that solve Laplace's equation to introduce coordinates on geometries with a toroidal topology. Using these coordinates we observe what we denote as the "cosmic voids and filaments" structure, even if no matter is present in the theory. We also show that if the scalar fields we used as coordinates are dynamically coupled to geometry, they can change it in a dramatic way. |
0903.4775 | Leonardo Fernandez-Jambrina | L. Fern\'andez-Jambrina, R. Lazkoz | Cosmological singularities and modified theories of gravity | 4pp, to appear in AIP Conference: Proc. XXXI Spanish Relat. Meeting,
ERE08, Salamanca, Spain, 15-19 Sept., 2008 | Physics and Mathematics of Gravitation: Proceedings of the Spanish
Relativity Meeting 2008, AIP Conference Proceedings Volume 1122, Eds. K.E.
Kunze, M. Mars, M.A. Vazquez-Mozo. AIP, Melville, 264-267, (2009) | 10.1063/1.3141286 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We consider perturbative modifications of the Friedmann equations in terms of
energy density corresponding to modified theories of gravity proposed as an
alternative route to comply with the observed accelerated expansion of the
universe. Assuming that the present matter content of the universe is a
pressureless fluid, the possible singularities that may arise as the final
state of the universe are surveyed. It is shown that, at most, two coefficients
of the perturbative expansion of the Friedman equations are relevant for the
analysis. Some examples of application of the perturbative scheme are included.
| [
{
"created": "Fri, 27 Mar 2009 11:13:30 GMT",
"version": "v1"
},
{
"created": "Sun, 29 Mar 2009 17:28:07 GMT",
"version": "v2"
}
] | 2015-05-13 | [
[
"Fernández-Jambrina",
"L.",
""
],
[
"Lazkoz",
"R.",
""
]
] | We consider perturbative modifications of the Friedmann equations in terms of energy density corresponding to modified theories of gravity proposed as an alternative route to comply with the observed accelerated expansion of the universe. Assuming that the present matter content of the universe is a pressureless fluid, the possible singularities that may arise as the final state of the universe are surveyed. It is shown that, at most, two coefficients of the perturbative expansion of the Friedman equations are relevant for the analysis. Some examples of application of the perturbative scheme are included. |
1401.7884 | Maximiliano Ujevic | M. Ujevic, P. S. Letelier and D. Vogt | Relativistic ring models | 13 pages, 6 figures | Int. J. Mod. Phys. D 20, 2291 (2011) | 10.1142/S0218271811020305 | null | gr-qc | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Relativistic thick ring models are constructed using previously found
analytical Newtonian potential-density pairs for flat rings and toroidal
structures obtained from Kuzmin-Toomre family of discs. In particular, we
present systems with one ring, two rings and a disc with a ring. Also, the
circular velocity of a test particle and its stability when performing circular
orbits are presented in all these models. In general, we find that regions of
non-stability appear between the rings when they become thinner.
| [
{
"created": "Thu, 30 Jan 2014 15:36:24 GMT",
"version": "v1"
}
] | 2014-01-31 | [
[
"Ujevic",
"M.",
""
],
[
"Letelier",
"P. S.",
""
],
[
"Vogt",
"D.",
""
]
] | Relativistic thick ring models are constructed using previously found analytical Newtonian potential-density pairs for flat rings and toroidal structures obtained from Kuzmin-Toomre family of discs. In particular, we present systems with one ring, two rings and a disc with a ring. Also, the circular velocity of a test particle and its stability when performing circular orbits are presented in all these models. In general, we find that regions of non-stability appear between the rings when they become thinner. |
1406.1297 | Valentin Kuzmichev | V. E. Kuzmichev, V. V. Kuzmichev (Bogolyubov Institute for Theoretical
Physics) | Quantum geometrodynamical description of the dark sector of the
matter-energy content of the universe | 18 pages, 6 EPS figures; v.2: a few sections and abstract are
revised, new references | Ukr. J. Phys. 2015. Vol. 60, No. 7, pp. 664-673 | 10.15407/ujpe60.07.0664 | null | gr-qc astro-ph.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The evolution of the universe is studied in exactly solvable dynamical
quantum model with the Robertson-Walker metric. It is shown that the equation
of motion which describes the expansion or contraction of the universe can be
represented in the form of the law of conservation of zero total energy for a
particle with arbitrary mass being an analogue of the universe. The analogue
particle moves in the potential well under the action of the internal force
produced by the curvature of space, matter, and pressures of classical and
quantum gravitational sources. At a definite stage of the evolution of the
universe, this force can perform the positive work on the universe, which is
similar to the work of the repulsive forces of dark energy, or it does the
negative work analogous to the work of the attractive forces of dark matter.
The cases of real and complex state vectors which describe the geometrical
properties of the universe filled with dust and radiation are considered. It is
shown that predictions of the quantum model do not contradict the observational
data about the accelerating expansion of our universe.
| [
{
"created": "Thu, 5 Jun 2014 08:35:03 GMT",
"version": "v1"
},
{
"created": "Thu, 6 Nov 2014 10:56:14 GMT",
"version": "v2"
}
] | 2015-10-20 | [
[
"Kuzmichev",
"V. E.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
],
[
"Kuzmichev",
"V. V.",
"",
"Bogolyubov Institute for Theoretical\n Physics"
]
] | The evolution of the universe is studied in exactly solvable dynamical quantum model with the Robertson-Walker metric. It is shown that the equation of motion which describes the expansion or contraction of the universe can be represented in the form of the law of conservation of zero total energy for a particle with arbitrary mass being an analogue of the universe. The analogue particle moves in the potential well under the action of the internal force produced by the curvature of space, matter, and pressures of classical and quantum gravitational sources. At a definite stage of the evolution of the universe, this force can perform the positive work on the universe, which is similar to the work of the repulsive forces of dark energy, or it does the negative work analogous to the work of the attractive forces of dark matter. The cases of real and complex state vectors which describe the geometrical properties of the universe filled with dust and radiation are considered. It is shown that predictions of the quantum model do not contradict the observational data about the accelerating expansion of our universe. |
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